R November, 1994

Home , Canyon Lake (Texas), Coleto Creek Reservoir, Lake Dunlap, Lake Wood

November, 1994 TRANS-TEXAS WATER PROGRAM WEST CENTRAL STUDY AREA

PHASE I INTERIM REPORT

VOLUME3

Prepared for

San Antonio River Authority San Antonio Water System Edwards Underground Water District Guadalupe-Blanco River Authority Lower Colorado River Authority Bexar Metropolitan Water District Nueces River Authority Texas Water Development Board

HDR Engineering, Inc. in association with Paul Price Associates, Inc. LBG-Guyton Associates Espey-Huston & Associates, Inc.

November, 1994 TRANS-TEXAS WATER PROGRAM WEST CENTRAL STUDY AREA PHASE I INTERIM REPORT

TABLE OF CONTENTS

VOLUME 1 Section Page ES EXECUTIVE SUMMARY ES-1

1.0 INTRODUCTION ...... 1-1 1.1 Study Area ...... 1-2 1.2 Objectives ...... 1-5

2.0 POPULATION, WATER DEMAND AND WATER SUPPLY PROJECTIONS ...... 2-1 2.1 Population Projections ...... 2-1 2.2 Water Demand Projections ...... 2-16 2.3 Water Supply Projections ...... 2-84 2.4 Water Demand and Supply Comparisons ...... 2-96

VOLUME 2

3.0 WATER SUPPLY ALTERNATIVES AND EVALUATIONS ...... 3-1 3.0.1 Environmental Overview ...... 3-7 3.0.2 Cost Estimating Procedures ...... 3-47

Conservation / Local Alternatives

3.1 Demand Reduction (L-10) ...... 3-57 3.2 Exchange Reclaimed Water for Edwards Irrigation Water (L-11) .... 3-73 3.3 Exchange Reclaimed Water for BMA Medina Lake Water (L-12) ... 3-91 3.4 Reclaimed Water Reuse (L-13) ...... 3-105 3.5 Transfer of Reclaimed Water to Corpus Christi Through Choke Canyon Reservoir (L-14) ...... 3-117 3.6 Purchase (or Lease) of Edwards Irrigation Water for Municipal and Industrial Use (L-15) ...... 3-127 3.7 Demineralization of Edwards "Bad Water" (L-16) ...... 3-147 3.8 Natural Recharge- Type 1 Projects (Maximum Size) (L-17) ...... 3-155 3.9 Natural Recharge- Type 2 Projects (Optimum Size) (L-18) ...... 3-171 3.10 Springflow Augmentation (L-19) ...... 3-185 3.11 Existing Water Rights in Nueces River Basin (N-10) ...... 3-207 Table of Contents. (continued)

VOLUME 2 (continued) Section Page

San Antonio River Basin

3.12 San Antonio River Unappropriated Streamflow (S-10, S-11, S-12) .. 3-211 3.13 Medina Lake (S-13) ...... 3-219 3.14 Applewhite Reservoir (S-14) ...... 3-235 3.15 Cibolo Reservoir (S-15) ...... 3-255 3.16 Goliad Reservoir (S-16) ...... 3-273

Guadalupe River Basin

3.17 Guadalupe River Unappropriated Streamflow (G-10, G-11, G-12, G-13, G-14) ...... 3-291 3.18 Diversion of San Marcos River Unappropriated Streamflow (G-13) . 3-303 3.19 Diversion of Guadalupe River at Lake Dunlap Unappropriated Streamflow (G-14) ...... 3-317 3.20 Canyon Lake (Released to Lake Dunlap) ( G-15) ...... 3-331 3.21 Cuero Reservoir (G-16) ...... 3-343 3.22 Lindenau Reservoir ( G-17) ...... 3-365 3.23 McFaddin Reservoir (G-18) ...... 3-389

Minor Reservoirs

3.24 Guadalupe River Dam 7 (G-19) ...... 3-407 3.25 Gonzales Reservoir (G-20) ...... 3-417 3.26 Lockhart Reservoir (G-21) ...... 3-423 3.27 Dilworth Reservoir (G-22) ...... 3-429

Colorado River Basin

3.28 Colorado River at Lake Austin (C-10, C-11, C-12, C-13) ...... 3-435 3.29 Colorado River at Columbus (C-14, C-15, C-16, C-17) ...... 3-459 3.30 Shaws Bend Reservoir (C-18) ...... 3-473

Brazos and Sabine River Basins

3.31 Aliens Creek Reservoir (B-10) ...... 3-485 3.32 Toledo Bend Reservoir (SB-10) ...... 3-503 3.33 Aliens Creek Reservoir and Toledo Bend Reservoir (SBB-10) ..... 3-517

ll Table of Contents (continued)

VOLUME 2 (continued)

Section Page

Carrizo Aquifer

3.34 Carrizo-Wilcox Aquifer (CZ-10) ...... 3-529

VOLUME3

3.35 Canyon Lake Area Water Supply (G-23) ...... 3-549 3.35.1 Description of Area with Projections of Population and Water Demand ...... 3-549 3.35.2 Available Yield ...... 3-553 3.35.3 Environmental Issues ...... 3-555 3.35.4 Water Quality and Treatability ...... 3-564 3.35.5 Engineering and Costing ...... 3-564 3.35.6 Implementation Issues ...... 3-568 3.36 Wimberley and Woodcreek Water Supply from Canyon Lake (G-24) ...... 3-571 3.36.1 Description of Area with Projections of Population and Water Demand ...... 3-571 3.36.2 Available Yield ...... 3-571 3.36.3 Environmental Issues ...... 3-575 3.36.4 Water Quality and Treatability ...... 3-580 3.36.5 Engineering and Costing ...... 3-580 3.36.6 Implementation Issues ...... 3-583 3.37 Northeast Hays and Northwest Caldwell Counties Water Supply from Near Lake Dunlap (G-25) ...... 3-585 3.37.1 Description of Area with Projections of Population and Water Demand ...... 3-585 3.37.2 Available Yield ...... 3-589 3.37.3 Environmental Issues ...... 3-592 3.37.4 Water Quality and Treatability ...... 3-594 3.37.5 Engineering and Costing ...... 3-594 3.37.6 Implementation Issues ...... 3-597 3.38 Mid-Cities (IH-35 and Highway 78) Water Supply From Near Lake Dunlap (G-26) ...... 3-599 3.38.1 Description of Area with Projections of Population and Water Demand ...... 3-599 3.38.2 Available Yield ...... 3-602 3.38.3 Environmental Issues ...... 3-606 3.38.4 Water Quality and Treatability ...... 3-608

lll Table of Contents (continued)

VOLUME 3 (continued) Section Page

303805 Engineering and Costing 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-608 303806 Implementation Issues 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-609 3.39 Lower Guadalupe River Basin Water Requirements 0 0 0 0 0 0 0 0 0 0 0 0 0 3-613 303901 Description of Area with Projections of Population and Water Demand 0 0 0 0 0 0 0 . 0 0 0 0 . 0 0 0 . 0 0 0 0 0 0 0 0 0 0 . 0 0 0 . 0 0 0 3-613 3.40 Guadalupe River Diversion Near Lake Dunlap with Transfer

of Downstream Rights (G-27) 0 0 o • 0 0 0 0 . 0 0 0 0 0 0 . 0 0 0 0 0 0 . 0 0 .. 0 0 3-619 3.40.1 Description of Alternative 0 0 0 0 0 0 0 0 0 0 0 . 0 0 0 . 0 0 0 0 0 0 0 . 0 0 . 3-619 3.40.2 Available Yield 0 0 0 0 . 0 0 . 0 . 0 0 . 0 0 . 0 0 0 . 0 0 . 0 0 0 . 0 0 . 0 0 0 .. 3-620 3.4003 Environmental Issues 0 . 0 0 . 0 . 0 0 0 0 0 . 0 0 0 0 . 0 . 0 0 0 0 0 0 .. 0 0 3-626 3.40.4 Water Quality and Treatability 0 . 0 0 0 0 0 .. 0 0 0 0 0 0 0 0 0 0 . 0 0 . 3-633

3.40.5 Engineering and Costing 0 o 0 0 o 0 0 0 0 0 0 0 . 0 0 0 o 0 0 0 0 0 0 0 0 0 . 0 3-633 3.4006 Implementation Issues 0 0 0 0 . 0 . 0 0 0 . 0 0 0 0 0 . 0 0 . 0 0 0 0 0 0 . 0 0 0 3-635 3.41 Guadalupe River Diversion Near Gonzales with Transfer of Downstream Rights (G-28) 0 . 0 . 0 0 . 0 .. 0 0 . 0 0 . 0 0 0 0 0 0 . 0 0 0 .. 0 3-639 3.41.1 Description of Alternative 0 0 0 0 0 . 0 0 0 0 0 0 0 0 0 0 0 0 0 . 0 0 . 0 0 0 . 3-639

3.41.2 Available Yield 0 .. o 0 . o • o 0 . o • 0 0 0 0 o • 0 0 0 0 0 0 . 0 0 0 . 0 0 .. 0 3-640

3.41.3 Environmental Issues o • 0 .. o 0 0 0 . 0 0 . 0 0 .. 0 o • 0 0 0 0 0 0 .. 0 . 3-646 3.41.4 Water Quality and Treatability 0 . 0 0 . 0 0 0 0 0 0 0 0 0 0 0 0 . 0 0 0 0 . 3-653

3041.5 Engineering and Costing . 0 o • 0 . 0 0 0 0 0 0 0 . 0 . 0 0 0 0 0 0 0 0 .. 0 . 3-653

3.41.6 Implementation Issues o • 0 . 0 .. 0 .. 0 0 . 0 0 . 0 0 0 . 0 0 . 0 0 .. 0 .. 3-654 3.42 Transfer of SAWS Reclaimed Water to Coleto Creek Reservoir (L-20) 3-657

3.42.1 Description of Alternative 0 . 0 o 0 0 0 . 0 0 0 0 0 0 0 0 0 0 0 0 0 0 . 0 0 0 0 3-657 3.42.2 Available Yield 0 0 0 . 0 0 . 0 . 0 0 . 0 . 0 0 0 0 .. 0 0 0 0 0 0 0 0 0 0 0 0 .. 0 3-657

3.4203 Environmental Issues 0 o • 0 . 0 0 . 0 0 . 0 0 . 0 0 0 0 0 0 . 0 0 . 0 0 0 . 0 0 3-664 3.42.4 Water Quality and Treatability 0 0 . 0 0 0 0 0 0 . 0 0 . 0 0 0 0 0 . 0 . 0 . 3-670

3.42.5 Engineering and Costing 0 . 0 0 . 0 . 0 . 0 o 0 0 0 0 0 . 0 0 . 0 0 0 . 0 ... 3-670 3.4206 Implementation Issues 0 0 0 0 0 . 0 . 0 0 . 0 0 0 .. 0 . 0 0 0 . 0 . 0 0 0 .. 0 3-671

lV Table of Contents (continued)

Section

APPENDICES Bound in Volume 2:

Appendix A - Report on Carrizo Aquifer

Appendix B - Protected Endangered and Threatened Species

Appendix C - Trans-Texas Environmental Criteria

Appendix D - GSA Basin Model - Parameter Summary Tables

Bound in Volume 3:

Appendix E - Summary Tables of Potential Water Supply Alternatives

Appendix F - SAWS Proposed Water Resource Plan

Appendix G - Canyon Lake Firm Yield

Appendix H - Water Rights Transfers and Firm Availability Analyses

Appendix I - Errata

v LIST OF TABLES

VOLUME 3

Table Title Page

3035-1 Population and Water Demand Projections Canyon Lake Area 0 0 0 0 0 0 0 0 0 3-552 3035-2 Canyon Lake Yield Available for Direct Diversion from Canyon Lake 0 0 0 0 o o 0 0 0 0 0 o 0 0 0 0 0 0 0 o o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-555 3.35-3 Protected Endangered and Threatened Species, Coma! County, Texas 0 0 0 0 0 0 0 0 0 0 0 0 0 o o 0 0 0 0 0 o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-559 3o35-4 Cost Estimate Summaries for Canyon Lake Regional Plan (G-23) 0 0 0 0 0 0 0 3-566 3o36-1 Population and Water Demand Projections Wimberley and Woodcreek Areas of Hays County 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-573 3036-2 Canyon Lake Yield Available for Direct Diversion from Canyon Lake 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-575 3.36-3 Important Species Known to Occur in the Study Area 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-578 3036-4 Cost Estimate Summaries for Wimberley and Woodcreek Supply from Canyon Lake (G-24) 0 o o o 0 0 0 o o 0 0 0 0 0 0 0 0 o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-582 3037-1 Population and Water Demand Projections Northeast Hays/ Northwest Caldwell Counties 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-588 3037-2 Canyon Lake Yield Available for Diversion at Lake Dunlap 0 0 0 0 0 0 0 0 0 0 0 3-591 3.37-3 Cost Estimate Summaries for Northeast Hays and Northwest Caldwell Counties Water Supply (G-25) o o o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-596 3.38-1 Population Projections Mid Cities (IH-35 and Highway 78) Areas 0 0 0 0 0 0 0 3-601 3.38-2 Water Demand Projections (Acft/Yr) Mid-Cities (IH-35 and Highway 78) Areas 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-603 3038-3 Canyon Lake Yield Available for Diversion at Lake Dunlap 0 0 0 0 0 0 0 0 0 0 0 3-605 3038-4 Cost Estimate Summaries for Mid-Cities (IH-35 and Highway 78) Water Supply (G-26) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-610 3039-1 Population and Water Demand Projections Lower Guadalupe Basin Area 0 0 0 0 0 0 0 0 0 o 0 0 0 0 0 0 o 0 0 0 0 0 0 o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-615 3.40-1 Canyon Lake Firm Yield Available for Diversion at Lake Dunlap 0 0 0 0 0 0 0 3-623 3.40-2 Firm Availability at Lake Dunlap with Selected Water Rights Transfers 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-625 3.40-3 Cost Estimate for Guadalupe River Diversion near Lake Dunlap with Transfer of Downstream Rights (G-27) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-634 3.40-4 Cost Estimate for Guadalupe River Diversion near Lake Dunlap with Transfer of Downstream Rights (G-27) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-636 3.41-1 Canyon Lake Firm Yield Available for Diversion at Gonzales 0 0 0 0 0 0 0 0 0 3-643 3.41-2 Firm Availability near Gonzales with Selected Water Rights Transfers 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-645 3.41-3 Cost Estimate Summaries for Guadalupe River Diversion near Gonzales with Transfer of Downstream Rights (G-28) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3-655

VI N

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CANYON POSSIBLE LAKE WATER TREATMENT

\ l

Legend TRANS TEXAS WATER PROGRAM I Possible Pipeline Route WEST CENTRAL STUDY AREA D Water Treatment Plant CANYON LAKE AREA WATER SUPPLY 0 2 4 Miles ALTERNATIVE G-23A ' 1-il~ ---Scale: 1"= 2 Miles HDR Engineering, Inc. FIGURE 3.35-1 3.35 Canyon Lake Regional Plan (G-23) 3.35.1 Description of Area with Projections of Population and Water Demand Construction of Canyon Lake was completed in 1964 and since that time, residential subdivisions have been platted around the lake and are being developed for both permanent homes and as dwellings for weekend and holiday visitors. To the southwest of Canyon Lake, in the scenic hill country of Comal County, the residential subdivisions of Smithson Valley, Oak Village North, and Bulverde have also been developing. These areas are shown on Figures 3.35-1 and 3.35-2. In both the lakeside and hill country subdivisions, water has been supplied to individual residences (homes and condominiums) by privatewater supply systems that are classified and regulated by the Texas Natural Resource Conservation Commission (TNRCC) as public water systems. The source of water for these systems is the underlying Trinity Group Aquifer, which is not adequate over the long term to meet the demands upon it, according to studies sponsored by the TWDB. Thus, a surface water system is needed in order to meet both the present needs and for growth. The Canyon Lake Regional Plan, as conceptualized in this study, consists of two separate water supply systems. One system would consist of a water treatment plant and treated water storage facilities located at Canyon Lake, with pipelines from the treatment plant to convey treated Canyon Lake water on a wholesale basis to the existing water supply systems around Canyon Lake (see Figure 3.35-1). The other system would contain similar facilities sized to supply Smithson Valley, Oak Village North, and Bulverde (see Figure 3.35- 2) for wholesale delivery to existing subdivision distribution systems. In the following discussion, the Texas Water Development Board (TWDB) high case, with conservation projections are given of population and the quantities of water needed for the Canyon Lake Regional System for the years 2000, 2010, 2020, 2030, 2040, and 2050. In addition, cost estimates are given for a treatment plant, storage facilities, and pipelines to convey treated water from the treatment plant to the subdivision wholesale delivery points. The population of the Canyon Lake regional water demand area, including estimates of temporary (weekend and holiday visitors) residents was 12,540 in 1990 and is projected to increase to 19,159 by 2000, to 33,837 by 2020, and to 53,028 by 2050 (Table 3.35-1). Of these totals, 78 percent was in subdivisions located around Canyon Lake in 1990, and 83 percent would be in Canyon Lake Subdivisions in 2050 (Table 3.35-1).

3-549 ':'-;:': __ :.:,')

~r "~.:.'.o~··.·.. ·.•. ".··:.~.! .•L·~· .. ."', •

POSSIBLE WATER TREATMENT PLANT LOCATION

Legend TRANS TEXAS WATER PROGRAM I Possible Pipeline Route WEST CENTRAL STUDY AREA D Water Treatment Plant

0 2 4 Miles CANYON LAKE AREA WATER SUPPLY ALTERNATIVE G-238 --- I I-il~ Scale; 1"= 2 Miles HDR Engineering, Inc. FIGURE 3.35-2 Table 3.35-1 Population and Water Demand Projections Canvon Lake Area Projection Date 1990 Area/Projection Actual 2000 I 2010 I 2020 I 2030.1 2o4o I 2050 Population 1 Canyon Lake Area Permanent Residents 2 7,340 10,353 13,914 17,811 21,711 25,198 27,834 Temporary Residents 3 2.500 5.000 7.500 10.000 12.500 15.000 16.000 Subtotal 9,840 15,353 21,414 27,811 34,211 40,198 43,834 Smithson Valley 600 846 1,086 1,339 1,582 1,813 2,044 Oak Village North 750 1,057 1,357 1,674 1,977 2,265 2,553 Bulverde 1.350 1.903 2.443 3.013 3.559 4,078 4.597 Total 12,540 19,159 26,300 33,837 41,329 48,354 53,028 Water Demand (ac-ft) 4 Canyon Lake Area Permanent Residents 5 1,233 1,739 2,337 2,992 3,647 4,233 4,676 Temporary Residents 5 119 239 358 478 597 717 765 Subtotal 1,352 1,978 2,695 3,470 4,244 4,950 5,441 Smithson Valley 99 147 162 183 215 254 300 Oak Village North 124 183 245 277 325 384 454 Bulverde 224 330 725 820 961 1,134 1.341 Total 1,799 2,638 3,827 4,750 5,745 6,722 7,536

Supply from Trinity Aquifer 6 1,799 1,799 1,799 1,799 1,799 1,799 1,799

Shortage 7 0 839 2,028 2,951 3,646 4,923 5,737 1 Texas Water Development Board high case projection. 2 Estimated from number of water meter connections, assuming 3.2 persons per connection, "Water Supply Study for Western Coma! County'', Guadalupe-Blanco River Authority, November, 1993. 3 Second residences for weekend and holiday use. Estimated from number of water meter connections, but this population is not included in Coma! County total population. 4 Texas Water Development Board high case projection, with conservation. 5 Calculated at 150 gallons per person per day; for temporary residents calculated at two days per week or 104 days per year. 6 Assuming continued use of existing wells. 7 Assumed to be supplied from Canyon Lake.

Estimated water use by the population of the Canyon Lake and neighboring hill country subdivisions in 1990 was 1, 799 acft (one acft is 325,851 gallons), of which 1,352 acft or 75 percent was used in Canyon Lake subdivisions (Table 3.35-1). All of this water was obtained from wells drilled into the underlying Trinity Group aquifer. As was noted earlier, this aquifer is not capable of continuing to meet the present plus the added demands of a growing population.

3-552 Future municipal water demands of the entire Canyon Lake regional area, as outlined above, are projected at 2,638 acft/yr in 2000, 4, 750 acft/yr in 2020, and 7,536 acft/yr in 2050 (Table 3.35-1). In year 2000, 75 percent of this demand would be in subdivisions located around Canyon Lake, with 72 percent of the total being needed in these lakeside subdivisions in 2050 (Table 3.35-1 ). If it is assumed that the present systems can continue to maintain and use their existing wells, then the demand upon Canyon Lake would be about 839 acft/yr in 2000, 2,028 acft/yr in 2010, 2,951 acft/yr in 2020, and 5,737 acft/yr in 2050 (Table 3.35-1) (Note: calculations are the difference between projected demands at each future decade and the quantity of water pumped from the aquifer (1,799 acft) in 1990.) However, if the present wells are abandoned, then the demands upon surface water from Canyon Lake would begin as soon as the surface water system is in place and would grow to 2,638 acft/yr in 2000, 4,750 acft/yr in 2020, and 7,536 acftjyr in 2050 (Table 3.35-1).

3.35.2 Available Yield The firm yield of Canyon Lake is defined to be the maximum amount of water the lake could have supplied through the drought of record after allowing for passage of inflows when required for senior (senior in time) downstream water rights. The drought of record for Canyon Lake covers a 116 month period of time which begins in July, 1947, and ends in February, 1957. Below Canyon Lake, there are senior water rights totaling more than 225,000 acft/yr that periodically require passage of lake inflows. When river flows originating below Canyon Lake exceed senior water rights requirements, inflows to the lake can be stored for later release. Springflow from the Edwards Aquifer contributes substantially to the base flow of the Guadalupe River and, consequently, provides water to meet a significant portion of downstream water rights, including GBRA and City of Seguin hydroelectric rights which are senior to Canyon Lake. If springtlow is decreased, due to dry weather and/or aquifer pumpage, a greater proportion of downstream senior water rights must be met by passage of Canyon Lake inflows making less water available for storage. Because springflow and downstream hydroelectric rights have direct effect on the firm yield of Canyon Lake, firm yield has been estimated for several alternative scenarios of hydroelectric rights subordination and aquifer pumpage. Subordination of hydroelectric

3-553 rights means that inflows to Canyon Lake are not subject to being called upon to meet a specified hydroelectric target flowrate downstream of Canyon. The Guadalupe- San Antonio River Basin Model 1 (GSA Model) has been modified and applied to compute the firm yield of Canyon Lake subject to two hydroelectric rights subordination scenarios and three aquifer pumpage scenarios for a total of six combined alternatives. The uncommitted firm yield is the portion of the total firm yield which is not presently committed to satisfy existing GBRA contracts. Refer to Appendix G for a detailed presentation of GSA model modifications and a complete summary of Canyon Lake firm yield analyses. Table 3.35-2 contains a summary of total firm yield and uncommitted firm yield available for diversion directly from Canyon Lake. Table 3.35-2 shows that with pumpage from the Edwards Aquifer set at 200,000 acft/yr through the period of record, the uncommitted firm yield of Canyon Lake (at the lake) is 20,100 acft/yr with a hydropower flow requirement of 365 cfs. If the hydropower requirement is reduced to 0 cfs, the uncommitted firm yield is 42,300 acft/yr. This is an increase of 22,200 acft/yr which represents a 38 percent increase in the total firm yield of Canyon Lake due to the subordination of the hydropower flow requirement. Table 3.35-2 also shows that with pumpage of the Edwards Aquifer set at 368,000 acft/yr and 400,000 acft/yr, the uncommitted firm yield of Canyon Lake (at the lake) is 8,400 acft/yr and 6,500 acft/yr respectively, with a hydropower flow requirement of 365 cfs. If the hydropower requirement is reduced to 0 cfs, the uncommitted firm yield is about 37,000 acft/yr for either aquifer pumpage scenario. For the 368,000 acft/yr aquifer demand scenario, the total firm yield of Canyon Lake increases from 46,800 acft/yr to 75,900 acft/yr (62 percent increase) when hydropower is subordinated to 0 cfs. For the 400,000 acft/yr aquifer demand scenario, the total firm yield of Canyon Lake increases from 44,900 acft/yr to 75,300 acft/yr (68 percent increase) when hydropower is subordinated to 0 cfs. Year 2050 projected water demand in the Canyon Lake area is 5,441 acft/yr (Table 3.35-1, with no groundwater supply) and availability of uncommitted Canyon Lake yield for all scenarios exceeds projected demands for the area. Therefore, the projected water demand for the area could be met with Canyon Lake yield provided a purchase contract is

1HDR Engineering, Inc., "Guadalupe- San Antonio River Basin Recharge Enhancement Study," Volumes I, II, and III, Edwards Underground Water District, September, 1993.

3-554 Table 3.35-2 Canyon Lake Yield Available for Direct Diversion from Canyon Lake Total Uncommitted Firm Firm Yield Yield 1 Aquifer Demand Hydropower 2 at Cany~/~J Lake at C~ny~iv Lake Scenario 3 Scenario (acft r) acft r)1 200,000 acft/yr 365 cfs 58 500 20100 0 cfs 80700 42,300 368,000 acft/yr 365 cfs 46 800 8400 0 cfs 75 900 37 500 400,000 acft/yr 365 cfs 44 900 6500 0 cfs 75 300 36,900 Notes: 1 Uncommitted firm yield is the portion of the total firm ~eld of Canyon Lake which has not been contractually committed. Existing contracts total 38,438 ac t/yr assuming an average of 6,000 acft/yr delivered to CP&L at Coleto Creek Reservoir. This includes 7,000 acft/yr to Canyon Regional Water Authority and Bexar Metropolitan Water Authority. 2 Hhdropower scenario represents the target flowrate f~ower generation at Lake Dunlap. 3 T e results of the simulated springflows from the DB Edwards Aquifer Model for all g.umpage scenarios were adjusted to account for the difference in the model's simulated historical spring ows and observed soringflows. signed with GBRA. For conceptual design, costing, and environmental analysis, the treatment and distribution system for both the Canyon Lake area and the Smithson Valley /Oak Village North/Bulverde corridor is sized to meet the year 2020 demands (Canyon Lake region: 3,470 acft/yr; Smithson Valley/Oak Village North/Bulverde corridor: 2,095, Table 3.35-1).

3.35.3 Environmental Issues Environmental Issues Overview This section is a comparative discussion of the potential environmental consequences and mitigation liabilities that would accompany implementation of centralized water supply alternatives for smaller municipalities and unincorporated areas north of the City of San Antonio. The Texas Water Development Board has adopted guidelines, developed cooperatively with Texas Parks and Wildlife Department, that outline major environmental concerns that must be addressed in evaluating the various water supply alternatives. These guidelines are for study purposes only and are not to be considered as permitting guidelines. The analyses in this report are not exhaustive environmental assessments, rather they have

3-555 been developed by reference to existing information in published reports, maps, aerial photography, unpublished documents and communications from government agencies, individuals, and private organizations. This information has been abstracted and summarized in order to provide a general review level of the environmental disturbance that would be associated with the construction of new water supplies systems. This general review and screening level discussion does not address secondary impacts, such as that portion of projected population and water use growth some consider to be created by the availability of new water supplies. A site specific level of investigation, focus on environmental concerns raised in public review of this document, and more detailed assessments of system operations or multiple combinations of sources will be the subject of future phases of the Trans Texas Water Program. Site specific studies of water supply alternatives selected for later phases will establish the actual requirements for the amount and timing of streamflows following impoundment or diversion and reductions in freshwater input to the brackish wetlands and shallow estuarine bays. In general, the following environmental discussions evaluate potential effects on the abundant important species in terms of habitat changes, while protected species are treated more individually, with a focus on determining the potential for an occurrence of those species or specific habitat features they may require at a proposed project feature. Protected species (and other important environmental features) are listed as possibly occurring in the vicinity of an alternative water supply facility when they have been credibly reported from a nearby (within a few miles) location, and the area occupied by the water supply facility is likely to include the appropriate environmental conditions (habitat) for an occurrence there. Important species include the local dominant (most abundant) species, species having some economic or recreational importance, those exerting disproportionate habitat impacts (habitat formers) and species listed, or proposed for listing as protected, by either the State of Texas or the federal government (protected species). The numerous unlisted species that are nevertheless of concern because of rarity, restricted distribution, direct exploitation or habitat vulnerability have not been included in the following discussions because the level of effort required to obtain the detailed distributional and life history information necessary to any meaningful evaluation is beyond that appropriate to a screening level survey. These

3-556 species will be addressed in subsequent phases of the Trans Texas Water Program, following review and comment by the biologists on the Technical Advisory Committees, and as site specific environmental evaluations are developed.

Alternative G-23A: Delivery of Surface Water to Areas Adjacent to Canyon Lake Environmental Setting Located on the Edwards Plateau in northwest Coma! County, Canyon Lake was constructed for water conservation and flood control on the Guadalupe River. Construction on the earth-fill dam was begun in 1958, deliberate impoundment of water was begun in June, 1964, and conservation pool elevation (909 ft MSL) was reached in 1968. Canyon Lake covers about 8,231 surface acres at conservation pool elevation (capacity 382,000 acre feet) and has an approximately 80 mile shoreline. The topography of the Edwards Plateau is generally flat to rolling over most of its surface, but the eastern margin, which includes Canyon Lake, is a highly dissected area of canyons and steep, well drained hillsides. Canyon Lake is on the Glen Rose formation, the oldest and most extensive Cretaceous rock unit in the vicinity. The thin interbedded hard and soft limestone, dolomite, and marl create the distinctive stair-step topography due to the varying resistance to erosion. Soils are mostly thin, brownish, calcareous gravely clay loams. In addition to the Guadalupe River, there are approximately five named creek drainages into Canyon Lake. These are Rebecca Creek, Schultz Creek, Potters Creek, Jentsch Creek and Tom Creek. Like most creek drainages in the area, they are intermittent, tending to cease flowing in the summer months, but maintaining isolated pools within their streambeds during some years. Where they intersect the shoreline, these and other unnamed drainages form variously sized, shallow coves that tend to support more wetland and mesic shoreline habitats than other areas. Emergent vegetation and broadleafed shrub in shoreline

2 wetlands is more common along the upper shoreline away from the dam • The vegetated shoreline is either grassed and gravely in the floodplain or gravel to juniper woods above flood level in the parks.

2U .S. Fish and Wildlife. 1990. National Wetland Inventory Map Series; Devils Backbone; Fischer; Sattler; and Smithson Valley, U.S. Geological Service Quadrangles, U.S. Department of the Interior.

3-557 The lake is primarily surrounded by residential and recreational developments, and public parks. In addition to Canyon Lake itself, the Guadalupe River above and below the lake is a popular recreational destination that has seen substantial shoreline development in recent years. Surrounding land use is predominantly rangeland with a spreading ring of suburban residential developments centered around the lake shore. Public access to scenic views and the lake shore is provided by the U.S. Corps of Engineers operated parks. Private marinas, restaurants, and vacation properties allow additional lake access to tourists and area residents. Randolph Air Force Base Recreational Area and the 5th Army Retreat are located on the north shore of the lake near the dam. Important species known in the project vicinity are listed in Table 3.35-3. However, the species listed in the table do not necessarily have habitat nor are specifically known to occur at the specific local of the alternative water supply facilities. This is a list of species and their preferred habitats that would be investigated or considered in a field survey program. In the case of migratory or transient species, the field survey would attempt to identify and evaluate habitat that may be attractive to these wandering species. Several of the birds listed above are migratory, transient, or historic in the county. Migratory and wandering birds included in the list are the Bald Eagle, Arctic Peregrine Falcon, the American Peregrine Falcon, Fulvous Whistling - duck, White-faced Ibis, White tailed hawk, and Wood Stork. The Bald Eagle is a rare winter resident in northern and north-central Texas along large lakes and rivers. A southern population breeds along the Texas Coast. Although historically common, the Bald Eagle has not been reported using or wintering on Canyon Lake. Bald Eagles are found in the more isolated lake and river habitats of the upper highland lakes, Lake Texoma and broad riparian corridors of the Gulf Coase.4. The project area possesses no habitats likely to be of significance to Arctic Peregrine Falcon or the American Peregrine Falcon. It is improbable that habitats as regionally widespread as those in the study would be limiting for these migratory species with such low population levels. The Arctic Peregrine Falcon, American Peregrine and Fulvous Whistling - duck all are found along the Gulf Coast where more and better food

30berholser, H.C. 1974. The Bird Life of Texas. 2 val. University of Texas Press, Austin, TX.

4 Rappole, J.H. and G.W. Blacklock.l994. A Field Guide Birds of Texas. Texas A&M Press, College Station, Texas.

3-558 Table 3.35-3 Protected Endangered and Threatened Species, Comal County, Texas Listing Agency 1 Potential Occurrence Common Name Scientific Name Habitat Preference USFWS I TPWD in Countv Bald Eagle Haliaeetus Large bodies of water E E wintering/ /eucocephalus with nearby transient roosting/ resting sites Peregrine Falcon, Falco peregrinus Open coastal areas E E migratory American anatum Peregrine Falcon, Falco peregrinus Open coastal areas T T migratory Arctic tundrius Swallow-tailed Elanoides Varied, open land with 3C T resident Kite, American forficatus tall trees for nesting White-tailed Buteo albicaudatus Grasslands and coastal NL T rare resident Hawk prairies Zone-tailed Hawk Buteo albonotatus Semi-aird canyon edges NL T historic of Southwest U.S. nesting Black-capped Vireo atricapillus Semi-open broad-leaved E E nesting/ Vireo shrub lands migrant Golden-cheeked Dendroica Woodlands with oaks and E E nesting/ Warbler chrysoparia old juniper migrant Interior Least Sterna antillantm Large river sandbars E E migratory Tern athalassos Whistling-duck, Dendrocygna Ponds and freshwater C2 NL resident Fulvous bicolor marshes White-faced Ibis Plegadis chihi Freshwater marshes C2 T resident Whooping Crane Grus americana Coastal wetlands; E E migrating Matagorda & Aransas islands Wood Stork Mycteria Post-breeding; in E' T dispersal americana wetlands of the coastal plain, major waterways, and lower Mississippi valley Cagle's Map Graptemys caglei Waters of the Guadalupe Cl NL resident Turtle River Basin Texas Horned Phrynosoma Open arid and semi-arid C2 T resident Lizard comutum regions with sparse vegetation; grass, cactus, scattered brush; soil may vary from sandy to rocky, burrows in soil, rodent burrow, or hides under rocks Texas Garter Thamnophis Varied, especially moist C2 NL resident Snake sirtalis annectans habitats Timber Crotalus horridus Bottomland hardwoods NL T possible Rattlesnake

3-559 Table 3.35-3 Protected Endangered and Threatened Species, Comal County, Texas Listing Agency 1 Potential Occurrence Common Name Scientific Name Habitat Preference USFWS I TPWD in Countv Tefa:s Ewycea neotenes Edwards Aquifer creeks C2 T resident Sa amander gravel bottom, emergent vegetation; underground & rocks, ledges Texas Mock- Philadelphus On limestone bluffs and C2 NL resident Orange texensis among boulders on tbe Edwards Plateau

1 E Endangered T Threatened 3C No Longer a Candidate for Protection C2 Candidate Category C1 Candidate Category, Substantial Information NL Not Listed

Source: Listed by the U.S. Department of the Interior (50 CFR 17.11 & 17.12, 16 April1990) Candidate Species (50 CFR 17, 6 January 1989; 21 February 1990; 21 November 1991) and Texas Parks and Wildlife Department (31 T.A.C. Sec. 65.171-174 & 65.181-184) sources and habitats may attract them for the winter or longer periods during migration. The White-tailed Hawk is found on the thorn brush and grassland savannas of South Texas along the coastal plain. It is a rare to casual resident of the Trans Pecos and Western

5 Edwards Plateau • The White Ibis and the Woodstork are transients in Texas. The White Ibis, uncommon in Comal County, is found mainly in marshes on the upper coastal plain in the summer. There are no breeding populations of the rare Woodstork in Texas. The lake and heavily wooded intermittent creeks possess little habitat that would appear useful to these transient marsh birds. The Interior Least Tern nests on sandbars of large rivers, primarily the Red River in Texas, and no resident populations have been recorded in Comal County. The Swallow tailed Kite was formerly reported in the coastal prairies to the Balcones Escarpment along riparian corridors. However, early in this century only widely separated nesting pairs were reported. Clearing activities in riparian woodlands and reduction of very tall (up to two hundred feet high) nesting trees may have limited this species nesting range to Louisiana

'Ibid.

3-560 6 to Florida in the United States • It is now a rare transient, mainly along the Texas coastal prairies and has no recorded breeding populations in Texas. Two birds, the Golden-cheeked Warbler and Black-capped Vireo, both listed as endangered by the U.S. Fish and Wildlife Service (USFWS), nest on the Edwards Plateau. Both species are known to nest in the vicinity of Canyon Lake in areas with suitable habitar7. The Golden-cheeked Warbler and the Black-capped Vireo are upland woodland/brushland species. Their breeding range includes Comal County. Although culturally induced changes in some apparently important features of habitat (e.g. dense brush patches amid an otherwise open woodland of oaks and junipers) have been suggested by ornithologists as reasons for decline of the species, nest parasitism by the Brown-headed Cowbird may be one of the most important causal factors. Endemic species such as the Texas salamander (Ewycea neotenes) are known to occur in springs and streams surrounding the lake. Cagle's map turtle ( Graptemys caglei ) and the Guadalupe bass are found in the Guadalupe River, Blanco River and throughout the upper

8 9 10 Guadalupe Basin • • These two river species use aquatic insects as their primary food •

11 Few Guadalupe bass have been found downstream of New Braunfels in Comal County • Cagle's map turtle which has been found in the lower Guadalupe River at Victoria at time of the year when flows are very high and areas that are riffles during the summer would be

12 runs during high flows •

60berholser, H.C. 1974. The Bird Life of Texas. 2 vol. University of Texas Press, Austin, TX.

7Texas Parks and Wildlife Department, Unpublished 1994. September, 1994, Data and map files of the Natural Heritage Program, Resource Protection Division, Austin, Texas.

8Gary P. Garrett. 1991. Guidelines for the Management of Guadalupe Bass. Texas Parks and Wildlife, Austin, Texas.

'Haynes, David and Ronald R. McKown. 1974. A new species of map turtle (Genus Graptemys) from the Guadalupe River System in Texas. Tulane Studies in Zoology and Botany, Vol.18, Num. 4. pp. 143-152.

10 Haynes, David and Ronald R. McKown. 1974. A new species of map turtle (Genus Graptemys) from the Guadalupe River System in Texas. Tulane Studies in Zoology and Botany, Vol.18, Num. 4. pp. 143-152.

"Gary P. Garrett. 1991. Guidelines for the Management of Guadalupe Bass. Texas Parks and Wildlife, Austin, Texas.

12Killebrew, Flavius C. and Dan A Porter. 1991. Testudines, Graptemys caglei. Herp Review: 22(1), p. 24.

3-561 Texas Horned Lizard (Phrynosoma comutum) is a denizen of open, well-drained habitats with sparse cover. Ants, spiders, and isopods are included in their diets. The habitat requirements of this lizard species could be met in the open areas. The decline of Texas horned lizard populations is associated with in invasion of fireants (Solenopsis invicta ), agricultural practices and urbanization. Conservation measures to restore this lizard include controlling the invading fireant without broadcast chemicals and maintenance of native

13 vegetation communities and corridors •

Effects Assessment The proposed waterline loop around Canyon Lake is estimated to be about 30 miles long, and to require a construction corridor width of 30 feet, within which vegetation and soils may be disturbed. The proposed water treatment plant would occupy less than ten acres, for a total area potentially disturbed during construction of 119 acres. A ten foot right of way (ROW), totaling 36.4 acres free of woody vegetation, would be maintained for the life of the project. The location of the proposed water treatment plant and the alignment of the water line around Canyon Lake is now only generally specified. The treatment plant would be located near Canyon Dam, while the water line would mostly parallel existing roadways (Figure 3.35-1 ). The land surrounding Canyon Lake in the vicinity of the water line shown in Figure 3.35-1 consists of about 60 percent live oak- ashe juniper savanna; 20 percent live oak -juniper woodland with areas of dense juniper thickets; 17 percent developed; and 3% wetland. Wetlands are primarily unvegetated, rocky, intermittent stream channels. Substantial numbers of relatively isolated rural residences are present within the savanna and woodlands. Resource conflicts can generally be avoided or minimized by careful site and alignment selection, avoiding, for example, springs and vegetated wetlands where the pipeline crosses a stream channel, and mesic, wooded slopes. Two candidate species, the Texas salamander (Eurycea neotenes) and the Texas mock-orange (Philade/phus texensis), and two endangered species, the Golden-cheeked Warbler and Black-capped Vireo, are

"Price, A., W. Donaldson, and J. Morse. 1993. Final Report As Required by the Endangered Species Act, Section 6, Texas Project No. E-1-4. Texas Parks and Wildlife Department, Austin, Texas.

3-562 species most likely to be in conflict with portions of this alternative, but those conflicts should be easily avoidable with appropriate habitat and species surveys. However, no mapped occurrences of important species showed direct conflict with the general facilities layout. Where any ROW clearing and construction activity may affect a federally protected species, consultation with the U.S. Fish and Wildlife Service (FWS) concerning the need for a permit for the incidental take of that species should be conducted. This level of study would occur during facility siting studies in later phases. A cultural resources survey of all public property, including easements held by public entities, to be disturbed during construction is required by the Antiquities Code of Texas (Title 9, Chapter 191, Texas Natural Resources Code of 1977). Any sites located would be tested for significance and eligibility for the National Register. Disturbance of significant sites should be avoided to the extent possible.

Alternative G-23B: Delivery of Surface Water to Smithson Valley, Oak Village North, and Bulverde Environmental Setting The area potentially affected by this alternative extends about ten miles south of Canyon Lake and encompasses a landscape very similar to the uplands surrounding the lake. The corridor that would be traversed by the water pipeline assessed as Alternative G-23B consists primarily of live oak - ashe juniper savanna (56 percent), and mesquite invaded rangeland (40 percent). Developed areas total 3 percent and wetlands occupy about 1 percent of the study corridor. There are relatively few streams, and perched ponds supply water for livestock. The streams are typically intermittent and similar to other streams around Canyon Lake. Important species listed in Table 3.35-3 apply to this potential water supply system.

Effects Assessment The Smithson to Bulverde waterline, would mostly parallel existing roadways, and would be 8.2 miles long, with a branch water line from State Highway 311 to Oak Village North that would be 2.4 miles long (Figure 3.35-2). The 10.6 miles of proposed water line would require a construction corridor of about 30 feet and a maintenance corridor of about 10 feet. Construction would involve the disturbance of soils and vegetation on up to 38.6

3-563 acres, and the long-term impacts of maintaining the ROW free of woody vegetation would affect about 15.8 acres, including the water plant site. Protected species that appear most likely to be encountered during construction of this alternative include the Texas Horned Lizard (Phrynosoma comutum), the Texas salamander (Eurycea neotenes) and the Texas mock-orange (Philadelphus texensis). Alignments chosen along existing roadways are less likely to include the Texas mock-orange. Potential conflicts should be easily avoidable with appropriate habitat and important species surveys. A cultural resources survey of all public property, including easements held by public entities, to be disturbed during construction is required by the Antiquities Code of Texas (Title 9, Chapter 191, Texas Natural Resources Code of 1977). Any sites located would be tested for significance and eligibility for the National Register. Disturbance of significant sites should be avoided to the extent possible.

3.35.4 Water Quality and Treatability [To be completed in subsequent phases of the study.]

3.35.5 Engineering and Costing For this alternative, surface water would be supplied from a treatment plant at Canyon Lake with water delivered on a wholesale basis to existing water utilities in the service area. For engineering and costing purposes, the delivery system around Canyon Lake is shown as a separate system from the delivery system for Oak Village North, Smithson Valley and Bulverde. Figures 3.35-1 and 3.35-2 show possible locations of water treatment plant sites and pipeline routes for each system, however, route studies and on-the ground surveys have not been performed. The possible facility locations are for reconnaissance - level studies for comparison of alternative projects. If the two systems were combined into a single system, the cost per acre-foot of water could be reduced.

Alternative G-23A: Delivery of Surface Water to Areas Adjacent to Canyon Lake This alternative would provide a surface water supply to the developing areas adjacent to Canyon Lake to augment the existing groundwater sources. A surface water

3-564 intake would be located as shown on Figure 3.35-1 in the general vicinity of the south end of Canyon Dam. From the intake, raw water would be pumped to a treatment plant located within two miles of the intake and from the treatment plant a pipeline would be constructed that loops around the lake and supplies water on a wholesale basis to existing distribution systems in each lakeside development. Treatment would consist of conventional surface water treatment (Treatment Level 3, Table 3.0-4). The treatment costs estimated for this alternative are for typical conventional treatment of surface water of average quality and are used for relative evaluation of alternatives. Treatability studies of Canyon Lake water may find that less expensive treatment methods are appropriate. The major facilities required to implement this alternative are: Reservoir Intake and Pump Station Raw Water Pipeline to Treatment Plant Water Treatment Plant (Level 3, Table 3.0-4, in Volume 2) Finished Water Pump Station Transmission Pipeline Interconnects to Retail Water Utilities Elevated Storage Tank or Standpipe The system has been sized for delivery of year 2020 demands of 3,470 acft/yr (3.1 mgd, average day) with a maximum day to average day peaking factor of 2.2. Therefore, the intake, treatment plant, and finished water pump station are sized for 6.8 mgd with an 18-inch diameter pipeline looping around the lake (about half of the flow branches each direction in the looped pipeline). The cost estimate for this alternative is summarized in Table 3.35-4. Operating costs were determined for a total static lift of 300 feet and an annual delivery of 3,470 acft. Financing the project over 25 years at an 8.0 percent annual interest rate results in an annual expense of $2,200,000 (Table 3.35-4 ). The annual cost of water purchased from GBRA is $53/acft, for a payment of about $184,000 per year. Operation and maintenance costs, including power and purchase of stored water total $1,254,000. The annual costs, including debt repayment, interest, and operation and maintenance, total $3,454,000. For an annual delivery of 3,470 acft, the resulting annual cost of water is $995 per acfe4 (Table 3.35-4). This is the cost of treated water for a relatively

14 Costs for supply systems in the GBRA planning areas, which have capacity to meet peak demands, are typically higher when compared to alternatives in Volume 2, which are mostly larger projects with uniform annual delivery rates.

3-565 Table 3.35-4 Cost Estimate Summaries for Canyon Lake Regional Plan (G-23) (Third Quarter - 1994 Prices) Alt. G-23 B Alt. G-23A Delivery to Delivery to Smithson Valley, Areas Adjacent Bulverde, and Oak Item to Canyon Lake Village North Capital Costs Intake and Treatment Plant $7,300,000 $4,310,000 Transmission Pipelines 8,700,000 5,090,000 Interconnects to Existing Systems 1,360.000 380.000 Total Capital Cost $17,360,000 $9,780,000 Engineering, Contingencies, and Legal 4,860,000 3,050,000 Costs Land Acquisition 260,000 210,000 Environmental Studies and Mitigation 310,000 260,000 Interest During Construction 680.000 530.000 Total Project Cost $23,470,000 $13,850,000 Annual Costs Annual Debt Service $2,200,000 $1,300,000 Annual Operation and Maintenance 870,000 430,000 Purchase of Stored Water 184,000 68,000 Annual Power Cost 200,000 80.000 Total Annual Cost $3,454,000 $1,878,000 Annual Water Delivery (acftjyr) 3,470 1,280 Annual Cost of Water 1 $995/acft $1,467/acft

1 Cost of treated water delivered on a wholesale basis and does not include the operating cost of the distribution system. Costs for supply systems in the GBRA planning areas, which have capacity to meet peak demands, are typically higher when compared to alternatives in Volume 2, which are mostly larger projects with uniform annual delivery rates.

Note: The cost to mitigate for hydro generation lost to subordination, if any, is not included and will depend on the amount and owner of the subordinated right.

3-566 small scale stand alone water treatment and conveyance facility delivered on a wholesale basis with capacity to meet peak demands, but does not include the operating cost of the distribution system. The cost to mitigate for hydro generation lost to subordination, if any, is not included and will depend on the amount and owner of the subordinated right.

Alternative G-23B: Delivery of Surface Water to Smithson Valley, Oak Village North, and Bulverde

This alternative would provide a surface water supply and augment the existing groundwater sources in the developing areas of Comal County southwest of Canyon Lake, including the communities of Smithson Valley, Oak Village North, and Bulverde. A surface water intake site would be constructed as shown on Figure 3.35-2 on the south side of Canyon Lake. From the intake, raw water would be pumped to a treatment plant located within a two miles of the intake and from the treatment plant a pipeline would be constructed along FM 3159 and FM 1863 to supply water on a wholesale basis to existing distribution systems at each community. Treatment would consist of conventional surface water treatment (Treatment Level 3, Table 3.0-4 ). The treatment costs estimated for this alternative are for typical conventional treatment of surface water of average quality and are used for relative evaluation of alternatives. Treatability studies of Canyon Lake water may find that less expensive treatment methods are appropriate. The major facilities required to implement this alternative are: Reservoir Intake and Pump Station Raw Water Pipeline to Treatment Plant Water Treatment Plant (Level 3, Table 3.0-4, in Volume 2) Finished Water Pump Station Transmission Pipeline Interconnects to Retail Water Utilities Elevated Storage Tank or Standpipe The system has been sized for delivery of year 2020 demands of 1,280 acft/yr (1.1 mgd, average day) with a maximum day to average day peaking factor of 2.2. Therefore, the intake, treatment plant, and finished water pump station are sized for 2.5 mgd with an 18-inch diameter pipeline delivering the water along the first part of the route reducing to an 8-inch pipeline near the end of the route. The operating cost was determined for a total static lift of 600 feet and an annual delivery of 1,280 acft. Financing the project over 25

3-567 years at an 8.0 percent annual interest rate results in an annual expense of $1,300,000 (Table 3.35-4). The annual cost of water purchased from GBRA is $53/acft, for a payment of about $68,000 per year. Operation and maintenance costs, including power and purchase of stored water total $578,000. The annual costs, including debt repayment, interest, and operation and maintenance, total $1,878,000. For an annual delivery of 1,280 acft, the resulting annual cost of water is $1,467 per acfrt5 (Table 3.35-4 ). This is the cost of treated water for a stand alone system delivered on a wholesale basis and does not include the

16 operating cost of the distribution system • The cost to mitigate for hydro generation lost to subordination, if any, is not included and will depend on the amount and owner of the subordinated right.

3.35.6 Implementation Issues Requirements Specific to Amending the Canyon Lake Permit 1. If this alternative requires exceeding the current permitted average annual diversion from Canyon Lake of 50,000 acft, then a permit amendment will require: a. Application to the TNRCC b. Hydrologic studies substantiating requested firm yield. c. Environmental studies of in-stream flow and bay/estuary effects. d. Subordination of hydropower rights. e. Management of Edwards Aquifer by a regional agency to achieve the modeled aquifer pumpage/springflow scenario.

Requirements Specific to Treatment and Distribution 1. Necessary permits: a. U.S. Army Corps of Engineers Sections 10 and 404 dredge and fill permits for stream crossings and raw water intake. b. TNRCC Discharge Permit for settling basin supernatant. c. GLO Sand and Gravel Removal permits. d. TPWD Sand, Gravel, and Marl permit for river crossings. e. Coastal Coordinating Council review may be required. 2. Right-of-way and easement acquisition.

"The costs presented here are for relatively small stand alone systems and do not provide economics to size of larger volumes. Previous studies by GBRA to serve this area have included capacity for supplying treated water to other customers, including San Antonio, and thus, the cost per acre-foot, as estimated in those studies, ranges from $384 to $866 per acre-foot of water.

"Costs for supply systems in the GBRA planning areas, which have capacity to meet peak demands, are typically higher when compared to alternatives in Volume 2, which are mostly larger projects with uniform annual delivery rates.

3-568 3. Crossings: a. Highways and railroads b. Creeks and rivers c. Other utilities 4. Financing: a. Sponsoring entity must be identified and be able to incur debt to finance project. b. Participating entities must negotiate water purchase contracts with GBRA and establish appropriate rate structures.

3-569 THIS PAGE INTENTIONALLY LEFf BLANK.

3-570 3.36 Wimberley and Woodcreek Supply from Canyon Lake (G-24) 3.36.1 Description of Area with Projections of Population and Water Demand The unincorporated communities of Wimberley and Woodcreek are located next to each other near the Blanco River, within the Guadalupe River Basin, in Hays County, about 12 air miles to the northeast of Canyon Lake (Figure 3.36-1 ). As in the case of subdivisions around Canyon Lake, water has been supplied by water supply corporations, with water obtained from wells drilled into the Trinity Group aquifer, which is inadequate to meet all of the projected needs in the future. One potential source of additional water is Canyon Lake. This supply could be utilized by the construction of a pipeline that would bring treated water from a water treatment plant at Canyon Lake to the present water supply corporation systems (wholesale storage locations) for retail distribution through existing distribution systems. The TWDB high case, with conservation, population and municipal water demand projections for the Wimberley and Woodcreek communities are presented in Table 3.36-1. In 1990, the population of Wimberley was 3,276 and is projected to increase to 8,525 by 2050 (Table 3.36-1). The population of Woodcreek was 1,004 in 1990, with projections to 2050, of 5,526 people (Table 3.36-1). The total population for these two neighboring communities was 4,280 in 1990, with projections of 14,051 by 2050 (Table 3.36-1). In 1990, total water use in the Wimberley and Woodcreek communities was 673 acft (Table 3.36-1). For these two communities, projected water demands in 2020 are 1,424 acft, and in 2050 are 2,424 acft annually. If present levels of supply (673 acft/yr) from existing wells can be continued, then in 2050 an additional quantity of 1,751 acft/yr will need to be obtained from some other source, such as Canyon Lake (Table 3.36-1 ). Since the Trinity Group Aquifer is not expected to be able to continue to yield the quantities needed to meet present and projected needs of the local area, the quantity of water needed from other sources in year 2050 ranges from a low of 1,751 acft, as stated above, to the projected total demand of 2,424 acft (Table 3.36-1).

3.36.2 Available Yield The firm yield of Canyon Lake is defined to be the maximum amount of water the lake could have supplied through the drought of record after allowing for passage of inflows

3-571 F"' ," '• I '). ,. • ,... · -, ,. 1 ;I '"' _ ~ ~ 1 ''< ' i e' WIMBERLY AND \2'' " "fu ; ' . · >. / ;/. ,>·.-· . .:;. WOODCREEK 'i f;Jj~.:ji ~·::"Mi ~j. ~ ' \: .. ~"., "~1;'.: \ .. \'· ((4' -5. r .) . ·1-.ci'"-._. b / I. : ·. <~(:/"'-.. :\,y' I 1';, \ ~·- -~~-~· ., -;., I.. ) >< :-.~ i · •.. -·- ·.\

\ \ .,.

y.' .r,,. \ --~ )' '·

••••••~~ i .... .--. •• •• .,. • .....I ' ' ""· ..• ' ""t•······-·•···,·\ ' ~··· • .. -...... ¥ . ·'-., ""j ~ 'I ••;_ ...... , P,OSSIBLE . ";~·~. '. "... ' CANYON LAKE ,. "/ REGIONAL SUPPLY' ·~, , / PIPELINE .•• •• ~J >' .. ••.. • :~ ~;t::.':"~-j· ~-/;74~_,, ' ~A<_:[ -/-. ~,.,_ . }, ' l; -·~";'7' ~- ~ ~, ··~~~~{.(' ·•;! !_.,_1 r_, _j '\ " , fo(p.u:(!·-- : I "":' • \ )k .,, ,.. ; . ·;· ,• CANYON r• .f ·I> ••:,., I ' POSSIBLE c<> • .<'l't~,;.:'. ·' · LAKE · r' . :·'•''S~<":·"-''"'' ,. \ _:;,/.(,·.·.,;;·~·WATER TREATMENT ! / :.-~. ~'rf~:·~·PLANT LOCATION ·~ . ' :J.;,.,.:rl~·}_~;:J __ ·::, _.:.::~~j. ~';tf:. .--' -. ' 4. :, ---~:~~5~ :~{·~ .. ,.'·. ,. ' • . • Ji:-,. :· ~ . ·~~J~H'<~l/ .. ·Jl \•if!:./?/ i.!'' · ';(• ~.%', ';c ·; ,1' ·. :J';:<),. >-'' . : '7.-;SJ'{;''>,\"., ...... 1,· ~"·, •·;·};_• x:::- . )~I ....._, .·...... ·. .. '~i l/_ .. ~;; ·.:•: '·' I/)· .... '' ... ': ''·:, ,. ''"t'l-\1 ' ., "i· . .,.. J ...... , . ·~-/<~>.~/~ i._-. }>~:;. .; ~x~t~~~:-~J \';i{~,~~,_:~ft }j~ ";.~~:~~--~-; _.~·. __ .·-~~-< ..,-":. .". ";: .-~~: -~--~~ Legend TRANS TEXAS WATER PROGRAM I Possible Pipeline Route WEST CENTRAL STUDY AREA 0 Water Treatment Plant WIMBERLY AND WOODCREEK WATER 0 2 4 Miles SUPPLY FROM CANYON LAKE --- I Hl~ ALTERNA TlVE G-24 Scale; 1"= 2 Miles HDR Engineering, Inc. FIGURE 3.36-1 Table 3.36-1 Population and Water Demand Projections Wimberley and Woodcreek Areas of Hays County

Projection Date 1990 Area/Projection Actual 2000 J 2010 1 2020 1 2030 1 2040 1 2050 Population 1 Wimberley 2 3,276 4,151 5,329 6,389 7,241 8,078 8,525 Woodcreek 2 1,004 1,349 1,813 2,436 3,274 4400 5.526 Total 4,280 5,500 7,142 8,825 10,515 12,478 14,051 Water Demand (ac-ft) 3 Wimberley 2 515 656 848 1,031 1,176 1,357 1,471 Woodcreek 2 158 213 288 393 532 740 953 Total 673 869 1,136 1,424 1,708 2,097 2,424

Supply from Trinity Aquifer 4 673 673 673 673 673 673 673 Shortage 0 196 463 751 1,035 1,424 1,751 1 Texas Water Development Board high case projection. 2 Source calculated from information in "Hays County Water and Wastewater Study", Hays County Water Development Board, San Marcos, Texas, 1989. 3 Texas Water Development Board high case projection, with conservation. 4 Assuming continued use of existing wells. when required for senior (i.e., senior in time) downstream water rights. The drought of record for Canyon Lake covers a 116 month period of time which begins in July, 1947, and ends in February, 1957. Below Canyon Lake, there are senior water rights totaling more than 225,000 acft/yr that periodically require passage of lake inflows. When river flows originating below Canyon Lake exceed senior water rights requirements, inflows to the lake can be stored for later release. Springflow from the Edwards Aquifer contributes substantially to the base flow of the Guadalupe River and, consequently, provides water to meet a significant portion of downstream water rights, including GBRA and City of Seguin hydroelectric rights which are senior to Canyon Lake. If springflow is decreased, due to dry weather and/ or aquifer pumpage, a greater proportion of downstream senior water rights demands must be met by passage of Canyon Lake inflows making less water available for storage. Because springflow and downstream hydroelectric rights have direct effect on the firm yield of Canyon Lake, firm yield has been estimated for several alternative scenarios of hydroelectric rights subordination and aquifer pumpage. Subordination of hydroelectric

3-573 rights means that int1ows to Canyon Lake are not subject to being called upon to meet specified hydroelectric target t1ow rates downstream of Canyon. The Guadalupe - San Antonio River Basin ModePx (GSA Model) has been modified and applied to compute the uncommitted firm yield of Canyon Lake subject to two hydroelectric rights subordination scenarios and three aquifer pumpage scenarios for a total of six combined alternatives. The uncommitted firm yield is the portion of the total firm yield which is not presently committed to satisfy existing GBRA contracts. Refer to Appendix G for a detailed presentation of GSA model modifications and a complete summary of Canyon Lake firm yield analyses. Table 3.36-2 contains a summary of estimated total firm yield and uncommitted firm yield available for diversion directly from Canyon Lake. Table 3.36-2 shows that with pumpage from the Edwards Aquifer set at 200,000 acft/yr through the period of record, the uncommitted firm yield of Canyon Lake (at the lake) is 20,100 acft/yr with a hydropower t1ow requirement of 365 cfs. If the hydropower requirement is reduced to 0 cfs, the uncommitted firm yield is 42,300 acft/yr. This is an increase of 22,200 acft/yr which represents a 38 percent increase in the total firm yield of Canyon Lake due to the subordination of the hydropower t1ow requirement. Table 3.36-2 also shows that with pumpage of the Edwards Aquifer set at 368,000 acft/yr and 400,000 acft/yr, the uncommitted firm yield of Canyon Lake (at the lake) is 8,400 acft/yr and 6,500 acft/yr respectively, with a hydropower t1ow requirement of 365 cfs. If the hydropower requirement is reduced to 0 cfs, the uncommitted firm yield is about 37,000 acft/yr for either aquifer pumpage scenario. This represents between a 62 and 63 percent increase in the total firm yield of Canyon Lake due to the elimination of the hydropower flow requirement. Year 2050 projected water demand in the Wimberley /Woodcreek area is 2,424 acft/yr (Table 3.36-1, with no groundwater supply) and availability of uncommitted Canyon Lake yield for all scenarios exceeds projected demands for the area. Therefore, the projected water demand for the area could be met with Canyon Lake yield provided a purchase contract is signed with GBRA. For conceptual design, costing, and environmental

1gHDR Engineering, Inc., "Guadalupe- San Antonio River Basin Recharge Enhancement Study," Volumes I, II, and III, Edwards Underground Water District, September, 1993.

3-574 Table 3.36-2 Can_y_on Lake Yield Available for Direct Diversion from Canyon Lake Total Uncommitted Firm Firm Yield Yield 1 Aquifer Demand Hydropower at Canyon Lake at Cany~iv Lake Scenario 3 Scenario 2 (acft/vr) (acft r)1 200,000 acftjyr 365 cfs 58 500 20100 0 cfs 80700 42300 368,000 acft/yr 365 cfs 46 800 8 400 0 cfs 75 900 37 500 400,000 acftjyr 365 cfs 44 900 6500 0 cfs 75 300 36 900 Notes: 1 Uncommitted firm yield is the portion of the total firm fteld of Canyon Lake which has not been contractually committed. Existing contracts total 38,438 ac t/yr assuming an average of 6,000 acft/yr delivered to CP&L at Coleta Creek Reservoir. This includes 7,000 acft/yr to Canyon Regional Water Authority and Bexar Metropolitan Water Authority. 2 Hhdropower scenario reresents the target flowrate fo{JDwer a:eneration at Lake Dunlap. 3 T e results of the simu ated springflows from the T B E wards Aquifer Model for alktumpage scenarios were adjusted to account for the difference in the model's simulated historical sprin ows and observed springflows. analysis, the treatment and distribution system is sized to meet the year 2020 demands (1,424 acft/yr, Table 3.36-1).

3.36.3 Environmental Issues The analyses in this report are not exhaustive environmental assessments, rather they have been developed by reference to existing information in published reports, maps, aerial photography, unpublished documents and communications from government agencies, individuals, and private organizations. These have been digested to provide a general review level of the environmental disturbance that would be associated with the production of new water supplies. This general review and screening level discussion does not address secondary impacts. A site specific level of investigation, focus on environmental concerns raised in public review of this document, and more detailed assessments of system operations or multiple combinations of sources will be the subject of future phases of the Trans Texas Water Program. Important species include the local dominant (most abundant) species, species having some economic or recreational importance, those exerting disproportionate habitat impacts

3-575 (habitat formers) and species listed, or proposed for listing, by either the State of Texas or the federal government (protected species). The numerous unlisted species that are nevertheless of concern because of rarity, restricted distribution, direct exploitation or habitat vulnerability have not been included in the following discussions because the level of effort required to obtain the detailed distributional and life history information necessary to any meaningful evaluation is beyond that appropriate to a screening level survey. These species will be addressed in subsequent phases of the Trans Texas Water Program, following review and comment by the biologists on the Technical Advisory Committees, and as site specific environmental evaluations are developed.

Environmental Setting Wimberley and Woodcreek communities are located about 12 miles northeast of Canyon Lake in Hays County on the Edwards Plateau. Wimberley and Woodcreek are located in a valley of the Blanco River at about 800 to 900 feet MSL (Figure 3.36-1). Spring fed Cypress Creek flows through the center of town. Large cypress trees line Cypress Creek and portion of the Blanco River. The scenic Wimberley area is a popular tourist destination. Both the Blanco River and Cypress Creek are heavily used recreational resources. Land use in Wimberley and Woodcreek is rural residential, suburban residential and recreational. Most of the surrounding land use is rangeland. Although an alignment study has not been performed, this report assumes that the waterline ROW's will cross the Blanco River west of the FM 12 crossing avoiding the mature cypress banks and springs at Wimberley. Alternative G-24 study corridor consists primarily of live oak - ashe juniper savanna (46% ), and mesquite invaded plateau live oak with midgrass series rangeland (48% ). Developed areas total 5% and wetlands occupy less than 1% of the study corridor. There are relatively few streams, and perched ponds supply water for livestock. These mostly unnamed creeks are typically intermittent and similar to small creeks around Canyon Lake.

3-576 Important water resources in the study corridor are the Blanco River, Cypress Creek and

19 20 2 22 a multitude of associated Edwards Aquifer springs • • 1. • Important species known to occur in Hays County and likely to have habitat within the study area are listed in Table 3.36-3. Although, the species listed in the table do not necessarily occur at the specific local of the alternative water supply facilities, this is a list of species and their preferred habitats that would be investigated, along with others known to Comal and Hays counties (see Table 3.35-3 and Appendix C of volume 2) or considered in a field survey program. In the case of migratory or transient species, the field survey would attempt to identify and evaluate habitat that may be attractive to these wandering species. The Golden-cheeked Warbler and Black-capped Vireo, both listed as endangered by the U.S. Fish and Wildlife Service (USFWS), are known to nest in Comal and Hays counties

3 in areas with appropriate habitae • The Golden-cheeked Warbler and the Black-capped Vireo are upland woodland/brushland species. Endemic species such as the Texas salamander are known to occur in springs along the Blanco River drainage basin. Cagle's map turtle and the Guadalupe bass are found in the Blanco River and through out the

24 25 upper Guadalupe Basin ' • Texas Horned Lizard is a denizen of open, well-drained habitats with sparse cover. The decline of Texas horned lizard populations is associated

19 USFWS. 1991. National Wetland Inventory Map Series. Devils Backbone and Wimberley, Texas Quadrangles. USGS.

20Texas Parks and Wildlife Department. Unpublished 1994. September, 1994, Data and map files of the Natural Heritage Program, Resource Protection Division, Austin, Texas.

21 Gould, F.W. 1975. Texas plants; a checklist and ecological summary. Texas A&M University. Texas Agricultural Experiment Station. MP-585/Rev. College Station, Texas.

22McMahan, CA., R.G. Frye, K.L. Brown. 1982. The Vegetation Types of Texas Including Cropland. Texas Parks and Wildlife Department, Austin, Texas.

23Texas Parks and Wildlife Department. Unpublished 1994. September, 1994, Data and map files of the Natural Heritage Program, Resource Protection Division, Austin, Texas.

24 Gary P. Garrett. 1991. Guidelines for the Management of Guadalupe Bass. TPWD Austin, Texas.

25 Haynes, David and Ronald R. McKown. 1974. A new species of map turtle (Genus Graptemys) from the Guadalupe River System in Texas. Tulane Studies in Zoology and Botany, Vo1.18, Num. 4. pp. 143-152.

3-577 Table 3.36-3 Important Species Known to Occur in the Study Area 1

Listing Agency ' Potential Common Summary of Habitat Occurrence Name Scientific Name Preference USFWS I TPWD in County Black-capped Vireo Semi-open broad-leaved E E nesting/ Vireo atricapillus shrub lands migrant Golden- Dendroica Woodlands with oaks and old E E nesting/ cheeked chrysoparia juniper migrant Warbler Blanco blind Typhlomolge Troglobitic; Stream bed of the E NL resident salamander robusta Blanco River

Texas Homed Phrynosoma Varied, sparse! y vegetated C2 T resident Lizard comutum uplands Texas Eurycea Edwards Aquifer creek gravel C2 T resident Salamander neotenes bottoms, emergent vegetation; underground & rocks, ledges Cagle's Map Graptemys Waters of the Guadalupe River Cl NL resident Turtle caglei Basin Guadalupe Micropterus Streams of eastern Edwards C2 NL resident Bass terculi Plateau Canyon Mock- Phiwdelphus Edwards Plateau C2 NL resident Orange emestii 1 Texas Parks and Wildlife Department. Unpublished 1994. September, 1994, Data and map files of the Natural Heritage Program, Resource Protection Division, Austin, Texas. 2 E Endangered T Threatened 3C No Longer a Candidate for Protection C2 Candidate Category C I Candidate Category, Substantial Information NL Not Listed with the invasion of fireants (Solenopsis invicta), agricultural practices and urbanization all

26 of which are present in the Wimberley and Woodcreek areas • Two species not discussed in Section 3.35.3 are the Blanco blind salamander and the hill country wild-mercury (Argythamnia aphoroides). The Blanco blind salamander is a troglobitic salamander found once in the Blanco River stream bed. Other populations of this little known troglobitic may be present in the Blanco River Basin. The hill country wild-

26 Price, A., W. Donaldson, and J. Morse. 1993. Final Report As Required by the Endangered Species Act, Section 6, Texas Project No. E-1-4. Texas Parks and Wildlife Department, Austin, Texas.

3-578 mercury, a plant, is listed in Hays County based on historic occurrence reports from before 1900.

Effects Assessment The waterline to Wimberley and Woodcreek from Canyon Lake, assumed to mostly parallel existing roadways, would be about 15 miles long (Figure 3.36-1 ). The proposed waterline would require a construction corridor of about 40 feet and a maintenance corridor of about 20 feet. Construction would involve the disturbance of soils and vegetation on up to 76 acres, and the long-term impacts of maintaining the ROW free of woody vegetation would affect about 40 acres, including the water plant site. One major stream crossing at the Blanco River would affect an estimated half acre of this lower perennial stream during construction and require about one-tenth acre permanent easement. Resource conflicts can generally be avoided or minimized by careful site and alignment selection, avoiding, for example, springs and vegetated wetlands where the pipeline crosses a stream channel, and mesic, wooded slopes. The Texas salamander, Blanco blind salamander, Texas mock-orange, Golden-cheeked Warbler and Black-capped Vireo are species most likely to be in conflict with portions of this alternative, but those conflicts should be easily avoidable with appropriate habitat and species surveys. Any future detailed assessment would include a complete review for Edwards Aquifer springs and karst associated species and important species with appropriate habitat. No mapped occurrences of important species showed direct conflict with the general facilities layout. Where any ROW clearing and construction activity may affect a federally protected species, consultation with the U.S. Fish and Wildlife Service (FWS) concerning the need for a permit for the incidental take of that species should be conducted. This level of study would occur during facility siting studies in later phases. A cultural resources survey of all public property, including easements held by public entities, to be disturbed during construction is required by the Antiquities Code of Texas (Title 9, Chapter 191, Texas Natural Resources Code of 1977). Any sites located would be tested for significance and eligibility for the National Register. Disturbance of significant sites should be avoided to the extent possible.

3-579 3.36.4 Water Quality and Treatability [To be completed in subsequent phases of the study.]

3.36.5 Engineering and Costing For this alternative, surface water supply for the Wimberley /Woodcreek area would be supplied from a treatment plant at Canyon Lake on a wholesale basis to existing water utilities in the service area. To create a cost effective project, this alternative would share a portion of the facilities for Alternative G-23A (Canyon Lake Regional Project), resulting in a project that is feasible only if G-23A is completed. (However, Alternative G-23A, Canyon Lake Regional Project is a stand-alone project, not requiring G-24 to be built.) The facilities common to both alternatives are the raw water intake, the water treatment plant, and the transmission pipeline from the treatment plant to the junction at FM 3424. Figure 3.36-1 is a vicinity map showing possible locations of a water treatment plant site and pipeline routes. For purposes of costing and general environmental assessment of this alternative, a surface water intake site is shown on Figure 3.36-1 in the general vicinity of the south end of Canyon Dam. From the intake, raw water would be pumped to a treatment plant located within two miles of the intake and from the treatment plant a 24 inch pipeline is required for the section common to the Canyon Lake loop, however the remainder of the Canyon Lake loop would be 18 inch diameter. At the junction with FM 3424, an 18-inch diameter pipeline will branch to Wimberley and Woodcreek to supply water on a wholesale basis to existing distribution systems. The waterline around the lake would also provide wholesale treated water to communities adjacent to Canyon Lake. Treatment would consist of conventional surface water treatment. The treatment costs estimated for this alternative are for typical conventional treatment of surface water of average quality and are used for relative evaluation of alternatives. Treatability studies of Canyon Lake water may find that less expensive treatment methods are appropriate. The major facilities required to implement this alternative are: Reservoir Intake and Pump Station Raw Water Pipeline to Treatment Plant Water Treatment Plant (Level 3, Table 3.0-4, Volume 2) Finished Water Pump Station Transmission Pipeline

3-580 Interconnects to Retail Water Utilities Elevated Storage Tank or Standpipe The portion of the facilities serving both Wimberley /Wood creek and the Canyon Lake region (i.e., water intake, raw water pumps, treatment plant, finished water pump station, and part of the transmission pipeline) have been sized for delivery of year 2020 demands of 4,894 acft/yr (3,470 acft to the Canyon Lake region plus 1,424 acft to Wimberley/Woodcreek for a total of 4.4 mgd, average day). With a maximum day to average day peaking factor of 2.2, the intake, treatment plant, and firushed water pump station are sized for 9.6 mgd with a 24-inch pipeline from the plant to the Wimberley/Woodcreek lateral intersection, reducing to an 18-inch diameter pipeline to Wimberley/Woodcreek. Table 3.36-4 contains the cost summary for the combined Canyon Lake Regional Plan and Wimberley/Woodcreek supply system in the first cost column. Cost Column 2 contains the costs for the Canyon Lake Regional Plan alone and Column 3 contains the difference in Column 1 and Column 2 which is the incremental cost of the Wimberley/Woodcreek Supply Plan. The operating cost for the combined system was determined for a total static lift of 300 feet and an annual delivery of 1,424 acft to WimberleyjWoodcreek and 3,470 acft to the Canyon Lake region. Financing the combined system over 25 years at an 8.0 percent annual interest rate results in an annual expense of $3,020,000 (Table 3.36-4 ). The annual cost of water purchased from GBRA is $53/ acft, for a payment of $259,000 per year. Operation and maintenance costs, including power and purchase of stored water total $1,629,000. Total annual costs, including debt repayment, interest, and operation and maintenance, total $4,649,000. For an annual delivery of 4,894 acft, the resulting annual cost of water is $950 per acfe7 (Table 3.36-4), and the incremental cost of the Wimberley/Woodcreek portion of the system is about $839 acft/yr. This is the cost of treated water delivered on a wholesale basis and does not include the operating cost of the distribution system. The cost to mitigate for hydro generation lost to subordination, if any, is not included and will depend on the amount and owner of the subordinated right.

27 Costs for supply systems in the GBRA planning areas, which have capacity to meet peak demands, are typically higher when compared to alternatives in Volume 2, which are mostly larger projects with uniform annual delivery rates.

3-581

------·------Table 3.36-4 Cost Estimate Summaries for Wimberley and Woodcreek Supply from Canyon Lake (G-24) (Third Quarter- 1994 Prices)

AJt G-23A with G-24 Alt G-23A Alt G-24 Canyon Lake Regional Stand Alone Incremental Cost Plan Combined with Canyon Lake Wimberley/ Item WimberleyJWoodcreek Regional Plan , Woodcreek Supply Capital Costs Intake and Treatment Plant $8,950,000 ($7,300,000) $1,650,000 Transmission Pipelines 12,400,000 (8, 700,000) 3,700,000 Interconnects to Existing Systems 1.580.000 (1,360 000) 220,000 Total Capital Cost $22,930,000 ($17 ,360,000) $5,570,000 Engineering, Contingencies, and Legal 7,330,000 (4,860,000) 2,050,000 Costs Land Acquisition 360,000 (260,000) 100,000 Environmental Studies and Mitigation 440,000 (310,000) 130,000 Interest During Construction 1,240,000 (680,000) 540.000 Total Project Cost $32,300,000 ($23,470,000) $8,390,000 Annual Costs Annual Debt Service $3,020,000 ($2,200,000) $820,000 Annual Operation and 1,120,000 (870,000) 250,000 Maintenance Purchase of Stored Water 259,000 (184,000) 75,000 Annual Power Cost 250,000 (200,000) 50,000 Total Annual Cost $4,649,000 ($3,454,000) $1,195,000

Annual Water Delivery (acft/yr) 4,894 I 3,470 1,424 Annual Cost of Water 3 $950/acft $995/acft $839/acft 1 Sum of projected annual delivery to Canyon Lake Region plus Wimberley/Woodcreek in year 2020 (i.e., 3,470 acft/yr plus 1,424 acft/yr). 2 From Table 3.35-3. 3 Cost of treated water delivered on a wholesale basis and does not include the operating cost of the distribution system. Costs for supply systems in the GBRA planning areas, which have capacity to meet peak demands, are typically higher when compared to alternatives in Volume 2, which are mostly larger projects with uniform annual delivery rates.

Note: The cost to mitigate for hydro generation lost to subordination, if any, is not included and will depend on the amount and owner of the subordinated right.

3-582 3.36.6 Implementation Issues

Requirements Specific to Amending the Canyon Lake Permit (if required):

1. If this alternative requires exceeding the current permitted average annual diversion from Canyon Lake of 50,000 acft, then a permit amendment will require: a. Application to the TNRCC b. Hydrologic studies substantiating requested firm yield. c. Environmental studies of in-stream flow and bay/ estuary effects. d. Subordination of hydropower rights. e. Management of Edwards Aquifer by a regional agency to achieve the modeled aquifer pumpage/springflow scenario.

Requirements Specific to Treatment and Distribution

1. Necessary permits: a. U.S. Army Corps of Engineers Sections 10 and 404 dredge and fill permits for stream crossings. b. TNRCC discharge of water treatment plant settling basin blowdown and filter backwash. c. GLO Sand and Gravel Removal permits. d. TPWD Sand, Gravel, and Marl permit for river crossings. e. Coastal Coordinating Council review may be required. 2. Right-of-way and easement acquisition. 3. Crossings: a. Highways and railroads b. Creeks and rivers c. Other utilities 4. Financing: a. Sponsoring entity must be identified and be able to incur debt to finance project. b. Participating entities must negotiate water purchase contract with GBRA and establish rate structures.

3-583 THIS PAGE INTENTIONALLY LEFT BLANK.

3-584 3.37 Northeast Hays and Northwest Caldwell Counties Water Supply from Near Lake Dunlap (G-25)

3.37.1 Description of Area with Projections of Population and Water Demand The Northeast Hays/Northwest Caldwell counties area is located within the Guadalupe River Basin service area and contains the cities of Kyle and Buda along Interstate Highway 35 and areas within Hays and Caldwell counties to the east of these two cities in which residential subdivisions are located (Figure 3.37-1 ). The water supply for Buda, and Goforth and Plum Creek Water Supply Corporation service areas is obtained from wells drilled into the Barton Springs Edwards Aquifer along its eastern boundary, which in this area is near Interstate Highway 35. In the case of Kyle and areas to the east of Kyle, water is obtained from wells drilled into the Edwards Aquifer. The Uhland, County Line, and Maxwell Water Supply Corporations (WSCs) have extended pipelines eastward from their Edwards wells and established retail distribution systems to supply their respective service areas of northeastern Hays and northwestern Caldwell Counties. However, in view of: (1) the fact that the Barton Springs Edwards Aquifer has limited capacity and may not be capable of meeting the growing demands that are being placed upon it, and (2) limitations are being placed upon pumpage from the Edwards Aquifer in order to maintain spring flows at San Marcos and Coma! Springs, and to protect endangered species of the aquifer, a supplemental water supply is needed for the Northeast Hays/Northwest Caldwell Counties area. One alternative is the development of a surface water treatment plant located alongside the Guadalupe River near Lake Dunlap, and construction of a treated water line from the plant to northeast Hays County, with wholesale delivery of treated surface water to the respective water supply corporation and city systems. This is the alternative selected for analysis in this study. Another approach would be to upsize a planned surface water treatment plant under consideration by the City of San Marcos. This plant would divert water from the San Marcos River downstream of the confluence with the Blanco River. A treated water line would need to be constructed to northeast Hays and northwest Caldwell counties, as described above. However, costs of this option have not been made in this study. (Note: San Marcos has purchased 5,000 acft/yr of Canyon Lake water and at the present time is in the process of planning a treatment plant to meet its needs. Thus, the timing is advantageous to consider the inclusion of both

3-585 Central Texas Plateau N

Texas Black/and 1 BARTON SPRING~ EDWARDS AQUIFER I AREA di:\\\\\¥~'1 :

Central Texas Plateau

-U

··~ Texas Black/and Prairies

POSSIBLE WATER TREATMENT PLANT LOCATION

1 j ! I , -L r

Legend TRANS TEXAS WATER PROGRAM I -- Basin Divide WEST CENTRAL STUDY AREA Possible Pipeline Route ~ Eooreglon 0 Water Treatment Plant NORTHEAST HAYS AND NORTHWEST CALDWELL COUNTlES WATER SUPPLY 0 10 20 Miles Hl~ ALTERNA TlVE G-25 II I I I I I Scale HDR Engineering, Inc. FIGURE 3.37-1 treatment plant and pipeline capacities needed to serve the Kyle/Buda/Northeast Hays/Northwest Caldwell Counties areas.) Projections of population and water demand are presented in Table 3.37-1. The population of the Northeast Hays/Northwest Caldwell counties areas in 1990 was 14,992, and is projected to increase to 41,393 in 2050 (Table 3.37-1). Of the Northeast Hays/Northwest Caldwell counties total population in 1990, 8,765 resided in areas served from the Barton Springs Edwards Aquifer and 6,227 resided in areas served from the Edwards Aquifer. Projections of population in 2050 for the Buda, Goforth WSC and Plum Creek WSC areas now served from the Barton Springs Aquifer are 25,384 (Table 3.37-1). For the Kyle, Uhland WSC, County Line WSC, and Maxwell WSC service areas, population is projected to increase from 6,227 in 1990 to 16,009 in 2050 (Table 3.37-1). San Marcos'

28 population in 1990 was 28,743, with projections to 2050 of 71,295 (Table 3.37-1 ). Water use from the Barton Springs Edwards Aquifer in the Northeast Hays County area in 1990 was 1,266 acft, with projected high case, with conservation water demands in 2050 of 3,788 acft annually for the Buda/Goforth/Plum Creek WSC service areas (Table 3.37-1). Water use from the Edwards Aquifer by Kyle, Uhland WSC, County Line WSC, and Maxwell WSC in 1990 was 953 acft, with projected demands for these service areas in 2050 of 2,502 acft annually (Table 3.37-1). San Marcos' water use in 1990 from the Edwards Aquifer was 6,321 acft; San Marcos projected 2050 water demands are 16,699 acft/yr (Table 3.37-1). Regulatory efforts to protect spring flows at Coma! and San Marcos Springs are expected to reduce the quantities of water available from the Edwards Aquifer and would

29 apply to all present users of Edwards Aquifer Water • Under the conditions of Senate Bill 1477, the estimated quantity of water available to the Northeast Hays/Northwest Caldwell Counties area from the Edwards Aquifer could be only 86 percent of the quantity that was

28 San Marcos projections are included for information purposes.

29Senate Bill 1477, Texas Legislature, Regular Session, 1993, specifies that maximum pumpage from the Aquifer through year 2007 can be no more than 450,000 acre-feet per year, and after 2007, must be reduced to 400,000 acre-feet per year, with the further condition that by 2012, there must be an Aquifer management plan which assures that flows from the springs will not be threatened. This latter condition plus the ever present possibility of droughts that result in less than normal runoff which recharges the Aquifer could result in even less pumpage during droughts than is specified by Senate Bill 1477.

3-587 Table 3.37-1 Population and Water Demand Projections Northeast Havs7Northwest Caldwell Counties Projection Date 1990 Area/Projection Actual 2000 I 2010 I 2020 I 2o3o I 2o4o I 2050 Population 1 Barton Springs Edwards Aquifer Area Buda 1,795 2,475 3,559 4,547 5,342 5,738 6,134 Goforth WSC 3,746 4,873 6,000 7,000 8,000 9,000 10,000 Plum Creek WSC 3.224 3.861 4.624 5,537 6.630 7.940 9,250 Subtotal 8,765 11,209 14,183 17,084 19,972 22,678 25,384 Edwards Aquifer Area Kyle 2,225 2,612 2,970 3,282 3,526 3,654 3,780 Uhland WSC 213 320 446 584 766 1,004 1,242 County Line WSC 834 997 1,192 1,425 1,703 2,036 2,369 Maxwell WSC 2.955 3.532 4,222 5.046 6,032 7.210 8.618 Subtotal 6,227 7,461 8,830 10,337 12,027 13,904 16,009 Total NE Hays/NW Caldwell 14,992 18,670 23,013 27,421 31,999 36,582 41,393 San Marcos' 28,743 36,320 46,477 55,459 63,205 67,250 71,295 Water Demand~ac-ft) 2 Barton Sprmgs dwards Aquifer Area Buda 174 363 486 591 682 726 no Goforth WSC 3 587 764 941 1,098 1,254 1,411 1,568 Plum Creek WSC 3 505 605 725 868 1.039 1,245 1.450 Subtotal 1,266 1,732 2,152 2,557 2,975 3,382 3,788 SupJWe from BS Edwards Aq er 4 1,266 1,266 1,266 1,266 1,266 1,266 1,266 Edwards Aquifer Area 326 474 509 537 569 577 585 Kl!tU and WSC 3 33 50 70 92 120 157 195 County Line WSC 3 131 156 187 223 267 319 371 Maxwell WSC 3 463 554 662 791 946 1.130 1.351 Subtotal 953 1,234 1,428 1,643 1,902 2,183 2,502 Total NE Haysj,NW Caldwell 2,219 2,966 3,580 3,900 4,8n 5,565 6,290 Supply from E wards Aquif~r ' 953 819 714 714 714 714 714 San Marcos ~M) Demand 6,321 9,357 11,453 13,232 14,939 15,819 16,699 Su~ly from dwards Aquifer (S ' 6,321 5,436 4,740 4,740 4,740 4,740 4,740

Projected NE Hays~NW Caldwell Shortage BS Edwards Aquifer Area 0 466 886 991 1,709 2,116 2,522 Edwards Aquifer Area 0 415 714 929 1.188 1,469 1.788 Total 0 881 1,600 1,920 2,897 3,585 4,310

1 Texas Water Development Board high case projection. 2 Texas Water Development Board high case proJection, with conservation. 3 Data from "Hays County Water and Wastewater Study'', Hays County Water Development Board, San Marcos, Texas, May, 1989; per catta water use at 140 gallons per person l?er day. 4 Assuming Barton Springs (BS) dwards Aquifer pumpage can be maintamed at the 1990 level. ' Assuming Edwards Aquifer pumpage will be reduced 25 percent of the 1990 level beginning in 2008 to protect spring flows (14 percent reduction between 1995 and 2008). During severe droughts the pumpage could be less than shown here. ' San Marcos oroiections are included for information onlv.

3-588 used in 1990 for the period 1995 through 2007, and beginning in 2008 could be about 75 percent of the quantity that was used in 1990. These estimates are based upon the 1990 Edwards Aquifer total pumpage of 519,796 acft, as reported to the Texas Water Development Board in surveys of water users, and the assumption that pumpage would be scaled back proportionately for all users in order to achieve the levels allowed under Senate Bill 1477. Given the conditions and assumptions stated above, the quantity of Edwards Aquifer water available to the Northeast Hays/Northwest Caldwell counties area annually for the period 1996 through 2007 would be about 819 acft/yr (Table 3.37-1; 953 acft x 0.86). If it is assumed that the Barton Springs Edwards Aquifer is capable of continuing to supply 1,266 acft of water per year to the Northeast Hays County area, then the quantity of water needed from other sources in the year 2000 for the Northeast Hays/Northwest Caldwell Counties area would be 881 acft (Table 3.37-1; 2,966 minus 1,266 minus 819 = 881), with an additional 3,921 acft needed for San Marcos, bringing the total needed in 2000 to 4,802 acft (Table 3.37-1). The projected quantities of surface water needed in 2010 for the Northeast Hays County area are 1,600 acft, with 714 acft needed for areas served from the Edwards Aquifer, and an additional 6,713 acft needed for San Marcos (Table 3.37-1 ). Projected quantities of water needed in 2050 for Northeast Hays County (area served from the Barton Springs Edwards Aquifer) are 2,522 acft, with 1,788 acft needed in Northeast Hays/Northwest Caldwell Counties area served from the Edwards Aquifer and 11,959 acft needed by San Marcos for a total of 16,269 acft (Table 3.37-1). (Note: San Marcos has purchased a supply of 5,000 acft/yr of Canyon Lake Water and is in the process of developing a plan to obtain and use this supply.)

3.37.2 Available Yield The firm yield of Canyon Lake is defined to be the maximum amount of water the lake could have supplied through the drought of record after allowing for passage of inflows when required for senior (senior in time) downstream water rights. The drought of record for Canyon Lake covers a 116 month period of time which begins in July, 1947, and ends in February, 1957. Below Canyon Lake, there are senior water rights totaling more than 225,000 acft/yr that periodically require passage of lake inflows. When river flows originating below Canyon Lake exceed senior water rights requirements, inflows to the lake

3-589 can be stored for later release. Springflow from the Edwards Aquifer contributes substantially to tlre base flow of the Guadalupe River and, consequently, provides water to meet a significant portion of downstream water rights, including GBRA and City of Seguin hydroelectric rights which are senior to Canyon Lake. If springflow is decreased, due to dry weather and/or aquifer pumpage, a greater proportion of downstream senior water rights demands must be met by passage of Canyon Lake inflows making less water available for storage. Because springflow and downstream hydroelectric rights have direct effect on the firm yield of Canyon Lake, firm yield has been estimated for several alternative scenarios of hydroelectric rights subordination and aquifer pumpage. Subordination of hydroelectric rights means that inflows to Canyon Lake are not subject to being called upon to meet specified hydroelectric target flow rates downstream of Canyon. The Guadalupe - San Antonio River Basin ModeP0 (GSA Model) has been modified and applied to compute the uncommitted firm yield of Canyon Lake (diverted at Lake Dunlap) subject to two hydroelectric rights subordination scenarios and three aquifer pumpage scenarios for a total of six combined alternatives. The uncommitted firm yield is the portion of the total firm yield which is not presently committed to satisfy existing GBRA contracts. Refer to Appendix G for a detailed presentation of GSA model modifications and a complete summary of Canyon Lake firm yield analyses. Table 3.37-2 contains a summary of the Canyon Lake estimated total firm yield and uncommitted firm yield available for diversion at Lake Dunlap. Table 3.37-2 shows that with pumpage from the Edwards Aquifer set at 200,000 acft/yr through the period of record, the uncommitted firm yield of Canyon Lake (at Lake Dunlap) is 21,200 acft/yr with a hydropower flow requirement of 365 cfs. If the hydropower requirement is reduced to 0 cfs, the uncommitted firm yield is 49,600 acft/yr. This is an increase of 28,400 acft/yr which represents a 48 percent increase in the total firm yield of Canyon Lake due to the subordination of the hydropower flow requirement. Table 3.37-2 also shows that with pumpage of the Edwards Aquifer set at 368,000 acft/yr and 400,000 acftjyr, the uncommitted firm yield of Canyon Lake (at Lake Dunlap) is 8,500 acft/yr and 6,600 acft/yr respectively, with a hydropower flow requirement of 365

30HDR Engineering, Inc., "Guadalupe- San Antonio River Basin Recharge Enhancement Study," Volumes l, II, and III, Edwards Underground Water District, September, 1993.

3-590 cfs. If the hydropower requirement is reduced to 0 cfs, the uncommitted firm yield is about 43,000 acft/yr for either aquifer pumpage scenario. This represents about a 75 percent increase in the total firm yield of Canyon Lake due to the elimination of the hydropower flow requirement.

Table 3.37-2 Canvon Lake Yield Available for Diversion at Lake Donlan Total Uncommitted Firm Firm Yield Yield 1 Aquifer Demand Hydropower at Lake x~nlap at Lake Dunlap Scenario 3 Scenario 2 (acft r) (acft/vr) 200,000 acft/yr 365 cfs 59 600 21200 0 cfs 88 000 49 600 368,000 acft/yr 365 cfs 46 900 8,500 0 cfs 82300 43 900 400,000 acft/yr 365 cfs 45,000 6600 0 cfs 81600 43 200 Notes: 1 Uncommitted firm yield is the portion of the total firm Pteld of Canyon Lake which has not been contractually committed. Existing contracts total 38,438 ac t/yr assuming an average of 6,000 acft/yr delivered to CP&L at Coleto Creek Reservoir. This includes 7,000 acft/yr to Canyon Regional Water Authority and Bexar Metropolitan Water Authority. 2 Hhdropower scenario rearesents the target flowrate ~wer g,eneration at Lake Dunlap. 3 T e results of the simu ated springflows from the B E wards Aquifer Model for all~umpage scenarios were adjusted to account for the difference in the model's simulated historical sprin ows and observed springflows.

Year 2050 projected water shortage in the Northeast Hays/Northwest Caldwell counties area is 4,310 acft/yr, including the estimated longterm supply from the Edwards Aquifer (Table 3.37-1) and availability of uncommitted Canyon Lake yield at Lake Dunlap for all scenarios exceeds projected shortages for the area. Therefore, the projected water demand for the area could be met with Canyon Lake yield provided a purchase contract is signed with GBRA. For conceptual design, costing, and environmental analysis, the treatment and distribution system is sized to meet the year 2020 demands (1,920 acft/yr, Table 3.37-1).

3-591 3.37.3 Environmental Issues Environmental Setting Alternative G-25 includes a water treatment plant located near Lake Dunlap. Lake Dunlap is on the Guadalupe River southeast of New Braunfels in Guadalupe County (Figure 3.37-1). The waterline would extend north along the western edge of the Blackland Prairie, just east of the Balcones Fault, through the northwest corner of Caldwell County into northeastern Hays County. The proposed alignment would require a river crossing of the San Marcos River east of IH 35. The headwaters of the Guadalupe River are in Kerr County, Texas, and it flows over 430 miles to San Antonio Bay on the Gulf of Mexico. The river is impounded by Canyon Lake and a series of small hydroelectric dams including the Guadalupe - Blanco River Authority dam at Lake Dunlap. The source waters of the river are surface runoff and springs. Two high volume spring systems, Coma! Springs and San Marcos Springs, are the sources of water for the Coma! and San Marcos Rivers which are major tributaries of the Guadalupe River below Canyon dam. Lake Dunlap is a long, moderately deep lake (average depth, 13 feet) with a surface area of about 420 acres filling the Guadalupe River channel just east of IH-35. Because the storage capacity of Lake Dunlap is small (5,900 acre-feet) relative to the normal discharge of the Guadalupe River, average residence time is short, thermal stratification is not persistent, and its effects on water quality are small. The land use and habitat in the water supply alternative area reflect its location at the western edge of the Blackland Prairies. The soils of the water line corridor range from light-colored, acid sandy loams (upland), dark-gray acid sandy loams and clays (bottomland) to fairly uniform dark-colored calcareous clays. Climax grasses of the Blackland Prairies are little bluestem, Indian grass, switch grass, purpletop, silver bluestem and Texas wintergrass as well as sideoats grama, hairy grama and tall dropseed. Unimproved pastures and abandoned croplands are invaded by mesquite. Post oak and blackjack oak are present as overstory, although only small remnants of this upland woodland are generally present in this ecoregion. Although the Texas Natural Heritage Program does not report endangered or threatened species directly along the proposed water line corridors or possible water

3-592 treatment plant site, some have been reported in the vicinity (Appendix B, Tables 10, 22 and

31 33, Volume 2) • The remnant areas of prairie grassland; brush and shrub invaded grassland; and rivers provide habitat for several endangered or threatened species. In upland habitats the Texas horned lizard and Texas garter snake may be present where habitat is appropriate. Coma! Springs and San Marcos Springs provide habitat for Edwards associated protected species. The upper Coma! and San Marcos Rivers have relatively constant temperature regime and stable water quality. From its headwaters to about 0.5 miles downstream of its confluence with the Blanco River, the San Marcos is critical habitat for the Texas wildrice, the fountain darter, and the San Marcos gambusia. These Edwards spring related species ranges do not extend into the Blackland Prairie ecoregion where the transmission line crossing would be located. The Cagle's map turtle, Guadalupe bass, and the blue sucker ranges extend from the Edwards Plateau through the Blackland Prairie to the Coastal Plains in the Guadalupe River. Cagle's map turtle has been located as far south as Victoria on the Coastal Plain. The Guadalupe bass may be found in Lake Dunlap. Streamflow is an important component of its habitat requirements. The Guadalupe bass, best adapted for flowing water, is often found in flowing water near riffles feeding on aquatic insects. Although the Guadalupe bass is found in reservoirs such as Canyon Lake, it may be at a competitive disadvantage with

32 other bass species in more lentic environments • The blue sucker, a large river fish, would not be present in Lake Dunlap.

Effects Assessment The waterline construction corridor is assumed to be a uniform 30 feet (ft) wide. Maintenance procedures would keep a 10 ft ROW free of woody vegetation. The water treatment plant and water line corridor are in an area that is predominantly cropland (80%) and a mixture of woods, brush and urban areas. The waterline construction ROWs would

31 TPWD. 1994. Unpublished data files and maps including species listed by the Texas Organization for Endangered Species, Natural Heritage Program, Resource Protection Division, Austin, Texas.

32Garrett, Gary P. 1991. Guidelines for the Management of Guadalupe Bass. Publication PWD-RP-N3200- 367-ll/91, Texas Parks and Wildlife Department, Austin, Texas.

3-593 result in disturbance to about 121 acres from Lake Dunlap. Permanently maintained ROW and the water treatment plant site will amount to an estimated 52 acres. The waterline from Lake Dunlap would cross the San Marcos River downstream of the critical habitat reach of the Texas wildrice, the fountain darter, and the San Marcos gambusia. Surveys for protected species or other biological resources of restricted distribution would be conducted within the proposed construction corridor where described habitat is present. With the majority of the water supply corridor and possible water treatment plant sites located in either cropland or urbanized areas, terrestrial impacts can generally be avoided or minimized by careful site selection. Erosion control measures would be implemented at stream crossings and the intake construction area, and following construction, the construction right-of-way (ROW) would be revegetated. Where any ROW clearing and construction activity may affect a federally protected species, consultation with the U.S. Fish and Wildlife Service (FWS) concerning the need for a permit for the incidental take of that species should be conducted. This level of study would occur during facility siting studies in later phases. A cultural resources survey of all public property, including easements held by public entities, to be disturbed during construction is required by the Antiquities Code of Texas (Title 9, Chapter 191, Texas Natural Resources Code of 1977). Any sites located would be tested for significance and eligibility for the National Register. Disturbance of significant sites should be avoided to the extent possible.

3.37.4 Water Quality and Treatability [To be completed in subsequent phases of the study.]

3.37.5 Engineering and Costing For this alternative, surface water supply for the Northeast Hays/Northwest Caldwell counties area would be supplied from a treatment plant located near Lake Dunlap to existing water utilities in the service area. This alternative would augment the existing groundwater supplies in the area by providing surface water on a wholesale basis to existing water supply companies. Figure 3.37-1 is a vicinity map showing possible locations of a water treatment plant site and pipeline routes.

3-594 For purposes of costing and general environmental assessment of this alternative, a surface water intake site was selected in the general vicinity of the south side of Lake Dunlap. From the intake, raw water would be pumped to a treatment plant located within two miles of the intake and from the treatment plant a pipeline would be constructed to supply water on a wholesale basis to existing distribution systems. Treatment would consist of conventional surface water treatment (Treatment Level 3, Table 3.0-4 ). The treatment costs estimated for this alternative are for typical conventional treatment of surface water of average quality and are used for relative evaluation of alternatives. Treatability studies of Canyon Lake water may find that less expensive treatment methods are appropriate. The major facilities required to implement this alternative are: Surface Water Intake and Pump Station Raw Water Pipeline to Treatment Plant Water Treatment Plant (Level 3, Table 3.0-4, in Volume 2) Finished Water Pump Station Transmission Pipeline Interconnects to Retail Water Utilities Elevated Storage Tank or Standpipe The system has been sized for delivery of year 2020 demands of 1,920 acft/yr (1.7 mgd, average day) assuming a maximum day to average day peaking factor of 2.2. Therefore, the intake, treatment plant, and finished water pump station are sized for 3.8 mgd with an 18-inch diameter pipeline beginning at the treatment plant and reducing to a 12-inch pipeline. The operating cost was determined for the total static lift of 160 feet and an annual delivery of 1,920 acft. Financing the project over 25 years at an 8.0 percent annual interest rate results in an annual expense of $1,560,000 (Table 3.37-3). The annual cost of water purchased from GBRA is $53/acft, for a payment of $102,000 per year. Operation and maintenance costs, including power and purchase of store water total $212,000. The annual costs, including debt repayment, interest, and operation and maintenance, total $2,312,000. For an annual delivery of 1,920 acft, the resulting annual cost of water is $1,204 per acfe3 (Table 3.37-3). This is the cost of treated water delivered on a wholesale basis and does not include the operating cost of the distribution system. The

33 Costs for supply systems in the GBRA planning areas, which have capacity to meet peak demands, are typically higher when compared to alternatives in Volume 2, which are mostly larger projects with uniform annual delivery rates.

3-595 Table 3.37-3 Cost Es.timate Summaries for Northeast Hays and Northwest Caldwell Counties Water Supply (G-25) (Third Quarter- 1994 Prices)

Item Alt G-25 Costs Capital Costs Intake and Treatment Plant $4,970,000 Transmission Pipelines 5,700,000 Interconnects to Existing Systems 840.000 Total Capital Cost $11,510,000 Engineering, Contingencies, and Legal Costs 3,710,000 Land Acquisition 230,000 Environmental Studies and Mitigation 280,000 Interest During Construction 940.000 Total Project Cost $16,670,000 Annual Costs Annual Debt Service $1,560,000 Annual Operation and Maintenance 540,000 Purchase of Stored Water 102,000 Annual Power Cost 110.000 Total Annual Cost $2,312,000 Annual Water Delivery (acft/yr) 1,920 Annual Cost of Water 1 $1,204/acft

Note: The cost to mitigate for hydro generation lost to subordination, if any, is not included and will depend on the amount and owner of the subordinated right.

3-596 cost to mitigate for hydro generation lost to subordination, if any, is not included and will depend on the amount and owner of the subordinated right.

3.37.6 Implementation Issues

Requirements Specific to Amending the Canyon Lake Permit

Requirements Specific to Treatment and Distribution

1. Necessary permits: a. U.S. Army Corps of Engineers Sections 10 and 404 dredge and fill permits for stream crossings. b. TNRCC Discharge Permit for settling basin supernatant. c. GLO Sand and Gravel Removal permits. d. TPWD Sand, Gravel, and Marl permit for river crossings. e. Coastal Coordination Council review may be required. 2. Right-of-way and easement acquisition. 3. Crossings: a. Highways and railroads b. Creeks and rivers c. Other utilities 4. Financing: a. Sponsoring entity must be identified and be able to incur debt to finance project. b. Participating entities must negotiate a water purchase contract with GBRA and establish rate structure.

3-597 •

TillS PAGE INTENTIONALLY LEFT BLANK.

3-598 3.38 Mid-Cities (IH-35 and Highway 78) Water Supply from Near Lake Dunlap (G-26) 3.38.1 Description of Area with Projections of Population and Water Demand The Mid-Cities area includes the southern corner of Coma! County, the western corner of Guadalupe County and adjacent areas in Northeastern Bexar County (Figure 3.38- 1). Interstate Highway 35 and State Highway 78 are major transportation corridors through the area. The communities of the area include Marion, Garden Ridge, Schertz, Cibolo, Selma, Universal City, Randolph Air Force Base, Live Oak, and Converse, plus unincorporated areas of western Guadalupe and southern Coma! Counties. These communities obtain their water supplies from the Edwards Aquifer and are faced with the same problem as was described in Section 3.37; i.e., limits on Edwards Aquifer pumpage to protect spring flows. The Mid-Cities area is quite similar to northeast Hays and northwest Caldwell counties, as described in Section 3.37 above, in that the cities and unincorporated areas have developed water systems which obtain their present water supply from the Edwards Aquifer. (Note: Within the past two or three years some surface water from the Guadalupe River has been added to the supplies of the area by the Canyon Regional Water Authority, and the City of New Braunfels to the east has developed a surface water supply which meets a part of its needs.) Since all Aquifer users are faced with potential reductions of present pumping levels in order to maintain flows at Comal and San Marcos Springs (see Section 3.37), it is necessary to develop water supplies from other sources. The most readily available supply is the Guadalupe River. Thus, a regional water supply system, which would convey treated surface water to the area from a water treatment plant at Lake Dunlap and make wholesale delivery via pipelines to the respective cities and water supply corporations' storage tanks for distribution through existing systems, could be developed to supply water to all or parts of the area. Projections of population and water demands of the Mid-Cities area are presented in Table 3.38-1. Cost estimates of water treatment plants and pipelines are given in later sections. In 1990, the population of the Mid-Cities service area located in southern Comal, western Guadalupe and parts of northwestern Bexar County served by Green Valley WSC, East Central WSC, and Bexar Met. LC/East was about 64,634 and is projected to increase to 151,169 by 2020, and 199,054 by 2050 (Table 3.38-1). The population of New Braunfels

3-599 NEW BRAUNFELS -'" /, ( LAKE ... :-v\.-:,,,\ . ' ' ' . DUNLAP N

;.,

"· POSSIBLE .. WATER TREATMENT PLANT LOCATION ,. ~

Central Texas, " Plateau ~ • /.!>( ~;_," ,• ,/ / ~~6 Texas

.~f \ Black/and 'I Prairies /. ,1 _, f '

Legend TRANS TEXAS WATER PROGRAM I -- Basin Divide Possible Pipeline Route WEST CENTRAL STUDY AREA ~ Ecoregion 0 Water Treatment Plant MID CITIES (IH-35 AND HWY 78) WATER 0 2 4 Miles SUPPLY FROM THE NEAR LAKE DUNLAP 1-il~ ALTERNATIVE G-26 Scale: 1"= 2 Miles --- HDR Engineering, Inc. FIGURE 3.38-1 Table 3.38-1 Population Projections 1 Mid-Cities (IH-35 and Highway 78) Areas

Projection Date 1990 Area Actual 2000 1 2010 1 2020 1 2030 1 2040-1 2050

ComalLGuadalu11e Counties Areas Garden Ridge 1,450 1,993 2,561 3,122 3,687 4,155 4,623 Selma 520 712 912 1,111 1,303 1,468 1,621 Schertz 10,141 13,630 15,423 17,156 19,401 21,074 22,747 Cibolo 1,757 2,715 3,802 4,569 5,141 5,690 6,239 Marion 2 984 1,309 1,676 1,945 2,149 2,350 2,545 Green Valley WSC 2 11,505 17,766 22,742 26,393 29,154 31,887 34,532 Crystal Clear WSC's 2 6,639 10,365 13,268 15,399 17,010 18,604 20,148 Springs Hill WSC's 2 3,839 15,343 19,641 22,794 25,179 27,539 29,823 East Central WSC 2 7,206 12,092 15,479 17,964 19,844 21,704 23,504 Bexar Met. LC/East 2 20,593 27.408 35,084 40,716 44976 49,192 53,272 Subtotal 64,634 103,333 130,588 151,169 167,844 183,663 199,054 Northeast Bexar County Areas Universal City 13,057 15,429 18,665 22,435 27,194 31,905 36,616 Randolph AFB 4,000 4,000 4,000 4,000 4,000 4,000 4,000 Live Oak 10,023 12,001 14,584 17,593 21,391 25,152 28,913 Converse 8,887 13.177 19,598 26.379 34,940 43,415 51,890 Subtotal 35,967 44,607 56,847 70,407 87,525 104,472 121,419

New Braunfels ' 27,334 33,300 40,792 47,011 54,691 57,930 61,641 Seguin . 18,853 20.298 21,873 24,686 26,410 27.876 29,343 Total 146,788 201,538 250,100 293,273 336,470 373,941 411,457 1 Texas Water Development Board, high case. 2 Projected at Texas Water Development Board's growth rates for Guadalupe County. Note: Service areas of Green Valley and East Central WSC's include parts of Northeast Bexar County, and Bexar Met. LC East obtains water from the Guadalupe River via purchase from the Guadalupe-Blanco River Authority through the Canyon Regional Water Authority. ' New Braunfels and Seguin included for information only.

33 was 27,344 in 1990 and is projected at 61,641 in 2050 (Table 3.38-1 ). The population of the Mid-Cities area of northeast Bexar County was 35,967 in 1990 and is projected to increase to 121,419 in 2050 (Table 3.38-1). The population of Seguin was 18,853 in 1990 and is projected to increase to 29,343 in 2050 (Table 3.38-1 ). Water use by customers of entities located in southern Comal, western Guadalupe and those parts of Northeastern Bexar County served by Green Valley WSC, East Central

33Although New Braunfels and Seguin are not included in the Mid-Cities plan, the population and water demand projections are included in Table 3.38-1 for information purposes.

3-601 WSC and Bexar Met. LC/East was 10,832 acft in 1990 and is projected to increase to 32,418 acft in 2050 (Table 3.38-2). Given the expected reductions in Edwards Aquifer pumpage under Senate Bill 1477 to maintain spring flows, the estimated supply of Edwards Aquifer water for the Southern Carnal/Western Guadalupe Counties Mid-Cities area after 2007 would be about 8,124 acft/yr except during severe droughts when it could be less. Under the conditions of Senate Bill 1477, the area is projected to need about 13,394 acft of Guadalupe River water in 2010, and the quantity would increase to about 24,294 acft/yr in 2050 (projected demands minus estimated supply from the Edwards Aquifer) (Table 3.38-2). Under Senate Bill 1477, for New Braunfels, the estimated quantities of water available from the Edwards Aquifer after 2007 would be about 4,690 acft/yr. Given this estimate, New Braunfels would need 6,779 acft of Guadalupe River water in 2010, and by 2050 would need an estimated 11,553 acft of Guadalupe River water. It is noted that New Braunfels has developed a surface water treatment plant and has obtained 6,720 acft of Canyon Lake water which is now being used. Water use in the Mid-Cities area of northeast Bexar County adjacent to southern Carnal and western Guadalupe counties in 1990 was 6,251 acft and water demand is projected to increase to 21,445 acft/yr in 2050 (Table 3.38-2). Given the expected reductions in Edwards Aquifer pumpage to maintain spring flows, the estimated supply of Edwards Aquifer water for this part of the Mid-Cities area after 2007 would be 4,688 acft/yr. Under conditions of SB 1477, as described above, this part of the Mid-Cities area would need 4,396 acft of additional supply in year 2000, 8,584 acft in 2020, and 16,757 acft in 2050 (shortages shown at bottom of Table 3.38-2). Water demands for Seguin increase from 3,604 acft in 1990 to 5,495 acft in 2050. Seguin has run-of-river municipal water rights to Guadalupe River flows of 7,000 acft, and a contract for 2,000 acft of Canyon Lake water, which would be expected to meet Seguin's needs except perhaps during severe droughts.

3.38.2 Available Yield The firm yield of Canyon Lake is defined to be the maximum amount of water the lake could have supplied through the drought of record after allowing for passage of inflows

3-602 Table 3.38-2 Water Demand Projections (AcftjYr) 1 Mid-Cities (IH-35 and Highway 78) Areas Projection Date 1990 Area Actual 2000 T 20101 2020 1 2030 1 2040 1 2050 ComalLGuadaluQe Counties Areas 2 Garden Ridge 397 650 800 941 1,103 1,233 1,363 Selma 134 156 182 244 286 322 356 Schertz 2,14D 2,84D 3,075 3,267 3,651 3,919 4,187 Cibolo 204 414 545 624 691 758 825 Marion 3 150 205 262 304 337 368 399 Green Valley WSC 3 1,804 2,785 3,566 4,138 4,571 5,000 5,415 Crystal Clear WSC's 3 1,042 1,625 2,080 2,414 2,667 2,917 3,159 Springs Hill WSC's 3 602 2,4D5 3,080 3,574 3,948 4,318 4,676 East Central WSC 3 1,130 1,896 2,427 2,816 3,111 3,4D3 3,685 Bexar Met. LC/East 3 3.229 4,297 5.501 6,384 7,052 7,713 8,353 Subtotal 10,832 17,273 21,518 24,706 27,417 29,951 32,418 Supply from Edwards Aquifer 4 10,832 9,315 8.124 8.124 8,124 8,124 8,124 Shortage 0 7,958 13,394 16,582 19,293 21,867 24,294 Northeast Bexar County Areas Universal City 2,323 3,4D5 3,910 4,473 5,361 6,218 7,075 Randolph AFB 1,494 1,635 1,582 1,528 1,514 1,501 1,488 Live Oak 1,221 2,473 2,842 3,252 3,882 4,536 5,190 Converse 1.213 2.258 3,139 4,019 5,244 6,468 7.692 Subtotal 6,251 9,771 11,473 13,272 16,001 18,723 21,445 Supply from Edwards Aquifer 4 6.251 5.375 4,688 4,688 4,688 4,688 4,688 Shortage 0 4,396 6,785 8,584 11,313 14,035 16,757

New Braunfels (NB) Demand ' 6,254 9,773 11,469 12,796 14,636 15,509 16,243 NB Supply from Edwards Aquifer 4 6.254 5.378 4,690 4,690 4,690 4,690 4,690 New Braunfels Shortage 0 4,395 6,779 8,106 9,946 10,819 11,553

Seguin Demand 5 3,604 4,365 4,484 4,811 5,059 5,277 5,495 Seguin Run-of-River/Canyon 9,000 9,000 9,000 9,000 9,000 9,000 9,000

Shortages Comal/Guadalupe Areas 0 7,958 13,394 16,582 19,293 21,867 24,294 Northeast Bexar County .Q 4,396 6,785 8,584 11.313 14,035 16.757 Total 0 12,354 17,179 25,166 30,606 35,902 41,051

1 Texas Water Development Board, high case, with conservation. 2 Service areas of Green Valley and East Central WSCs of Guadalupe County include parts of Northeast Bexar County, and Bexar Met. LC East obtains water from the Guadalupe River via purchase from the Guadalupe-Blanco River Authority through the Canyon Regional Water Authority. 3 Projected at 14D gallons per person per day. 4 Assuming pumpage will be reduced 25 percent of the 1990 level beginning in 2008 to protect spring flows (14 percent reduction between 1995 and 2008). During severe droughts pumpage could be less than shown here. 5 New Braunfels and Seguin are included for information purposes. Both cities use surface water from the Guadalupe River; Seguin has no Edwards Aquifer supply.

3-603 when required for senior (senior in time) downstream water rights. The drought of record for Canyon Lake covers a 116 month period of time which begins in July, 1947, and ends in February, 1957. Below Canyon Lake, there are senior water rights totaling more than 225,000 acft/yr that periodically require passage of lake inflows. When river flows originating below Canyon Lake exceed senior water rights requirements, inflows to the lake can be stored for later release. Springflow from the Edwards Aquifer contributes substantially to the base flow of the Guadalupe River and, consequently, provides water to meet a significant portion of downstream water rights, including GBRA and City of Seguin hydroelectric rights which are senior to Canyon Lake. If springflow is decreased, due to dry weather and/or aquifer pumpage, a greater proportion of downstream senior water rights must be met by passage of Canyon Lake inflows making less water available for storage. Because springflow and downstream hydroelectric rights have direct effect on the firm yield of Canyon Lake, firm yield has been estimated for several alternative scenarios of hydroelectric rights subordination and aquifer pumpage. Subordination of hydroelectric rights means that inflows to Canyon Lake are not subject to being called upon to meet specified hydroelectric target flow rates downstream of Canyon. The Guadalupe - San Antonio River Basin Model35 (GSA Model) has been modified and applied to compute the uncommitted firm yield of Canyon Lake (diverted at Lake Dunlap) subject to two hydroelectric rights subordination scenarios and three aquifer pumpage scenarios for a total of six combined alternatives. The uncommitted firm yield is the portion of the total firm yield which is not presently committed to satisfy existing GBRA contracts. Refer to Appendix G for a detailed presentation of GSA model modifications and a complete summary of Canyon Lake firm yield analyses. Table 3.38-2 contains a summary of the Canyon Lake estimated total firm yield and uncommitted firm yield available for diversion at Lake Dunlap. Table 3.38-3 shows that with pumpage from the Edwards Aquifer set at 200,000 acft/yr through the period of record, the uncommitted firm yield of Canyon Lake (at Lake Dunlap) is 21,200 acftjyr with a hydropower flow requirement of 365 cfs. If the hydropower requirement is reduced to 0 cfs, the uncommitted firm yield is 49,600 acftjyr. This is an

35 HDR Engineering, Inc., "Guadalupe- San Antonio River Basin Recharge Enhancement Study," Volumes I, II, and III, Edwards Underground Water District, September, 1993.

3-604 Table 3.38-3 Canvon Lake Yield Available for Diversion at Lake Dunlap Total Uncommitted Firm Firm Yield Yield 1 Aquifer Demand Hydropower at at L~ke :~~nlap Scenario 3 Scenario 2 ~~ket~~)lapacft r acft r) 200,000 acft/yr 365 cfs 59 600 21200 0 cfs 88 000 49600 368,000 acft/yr 365 cfs 46 900 8 500 0 cfs 82,300 43.900 400,000 acft/yr 365 cfs 45 000 6 600 0 cfs 81600 43 200 Notes: 1 Uncommitted firm yield is the portion of the total fum ~eld of Canyon Lake which has not been contractually committed. Existing contracts total 38,438 ac t/yr assuming an average of 6,000 acft/yr delivered to CP&L at Coleta Creek Reservoir. This includes 7,000 acftjyr to Canyon Regional Water Authority and Bexar Metropolitan Water Authority. 2 Hhdropower scenario represents the target flowrate f~wer ~eneration at Lake Dunlap. 3 T e results of the sumulated springflows from the B E wards Aquifer Model for all s,umpage scenarios wer~cli~justed to account for the difference in the model's simulated historical spring ows and observed sprin ows. increase of 28,900 acftjyr which represents a 48 percent increase in the total firm yield of Canyon Lake due to the subordination of the hydropower flow requirement. Table 3.38-3 also shows that with pumpage of the Edwards Aquifer set at 368,000 acftjyr and 400,000 acft/yr, the uncommitted firm yield of Canyon Lake (at Lake Dunlap) is 8,500 acft/yr and 6,600 acft/yr respectively, with a hydropower flow requirement of 365 cfs. If the hydropower requirement is reduced to 0 cfs, the uncommitted firm yield is about 43,000 acft/yr for either aquifer pumpage scenario. This represents about a 75 percent increase in the total firm yield of Canyon Lake due to the elimination of the hydropower flow requirement. Year 2050 projected water shortage in the Mid-Cities area is 41,051 acft/yr, including the estimated longterm supply from the Edwards Aquifer (Table 3.38-2). This quantity of Canyon Lake yield would only be available from the remaining uncommitted firm yield of Canyon Lake with full subordination of hydropower rights. Inter local agreements would be needed to secure the hydro subordination, manage aquifer demand to pre-determined limits, and commit the available yield to the Mid-Cities area. A conceptual water treatment and transmission facility design has been completed to meet the projected shortage assuming the

3-605 Canyon Lake yield would be available from and diverted at Lake Dunlap. For conceptual design, costing, and environmental analysis, the treatment and distribution system is sized to meet the year 2020 demands (25, 166 acft/yr, Table 3.38-2, includes longterm supply from the Edwards Aquifer).

3.38.3 Environmental Issues Environmental Setting The land use and habitat in water supply alternative G-26 area reflects its location at the confluence of the Blackland Prairies with the Post Oak Savannah vegetation regions. The soils of the area range from light-colored, acid sandy loams (upland), dark-gray acid sandy loams and clays (bottomland) to fairly uniform dark-colored calcareous clays. Post Oak Savannah grasses are little bluestem, Indian grass, switch grass, purpletop, silver bluestem and Texas wintergrass. The overstory is primarily post oak and blackjack oak. Savannah and grasslands have been invaded by mesquite brushlands. There are relatively few streams, and perched ponds supply water for livestock. Santa Clara Creek and Long Creek are the major creek crossings. These streams are intermittent tending to cease flowing in the summer months, but maintaining isolated pools within their streambeds during some years. The water lines are primarily in pasture and cropland (80%) and a mixture of woods, brush and urban areas. The southwestern quarter of the pipelines cross a region that is about 50% developed, 20% cropland and the remainder a mix of brush, shrub and grassland.

Effects Assessment The water line construction corridor is assumed to be a uniform 30 feet (ft) wide which is required for the size waterline described in Section 3.38.5. Maintenance procedures would keep a 10 ft ROW free of woody vegetation. The water line construction ROW and water treatment plant would result in disturbance to about 58 acres, and the long-term impacts of maintaining the ROW free of woody vegetation would affect about 36 acres, including the water plant site of mainly vacant cropland and unimproved pastures. The water line would cross several intermittent stream and effect less than a half acre of wetlands during construction and less than a tenth acre long term. Less than 0.25 acres of riparian

3-606 woodland along the Guadalupe River would be impacted during construction of the river intake structure. Although the Natural Heritage Program does not report any endangered or threatened species directly along the water line corridor (Appendix B, Table 6), the remnant areas of brush, shrub and grassland in northeastern Bexar County may provide habitat for several endangered or threatened species, such as the Texas Tortoise, Reticulate Collared Lizard, and the Indigo Snake. In upland habitats of Guadalupe County (Appendix B, Table 22), the Texas horned lizard and Texas garter snake may be present in appropriate areas. Surveys for protected species or other biological resources of restricted distribution would be conducted within the proposed construction corridor where described habitat is present. The Cagle's map turtle, Guadalupe bass, and the blue sucker ranges extend from the Edwards Plateau through the Blackland Prairie to the Coastal Plains in the Guadalupe River. Cagle's map turtle has been located as far south as Victoria on the Coastal Plain. Best adapted for flowing water, the Guadalupe bass is often found in flowing water near riffles feeding on aquatic insects and moving water associated fish such as the Texas shiner and channel catfish. Streamflow is an important component of its habitat requirements. Although the Guadalupe bass is found in reservoirs such as Canyon Lake, it may be at a

36 competitive disadvantage with other bass species in more lentic environments • Populations of Guadalupe bass tend to decline as the river enters the Coastal Plan. In the Guadalupe River, few are found downstream of Luling in Caldwell County. Although Lake Dunlap does not present a habitat that correlates with abundant population of Guadalupe bass, some may be found in Lake Dunlap. The blue sucker, a large river fish, is a candidate for federal protection with probable occurrence, although the presence of several dams in this reach of the Guadalupe, together with a lack of suitable substrate and flow conditions, suggests that it may no longer be present. Water supply alternative G-26 is located in mostly upland pastures, cropland or urbanized areas. Terrestrial impacts can generally be avoided or minimized by careful selection of the pipeline ROW. Erosion control measures would be implemented at stream crossings and following construction, the construction right-of-way (ROW) would be

36Garrett, Gary P. 1991. Guidelines for the Management of Guadalupe Bass. Publication PWD-RP-N3200- 367-11/91, Texas Parks and Wildlife Department, Austin, Texas.

3-607 revegetated. Where any ROW clearing and construction activity may affect a federally protected species, consultation with the U.S. Fish and Wildlife Service (FWS) concerning the need for a permit for the incidental take of that species should be conducted. This level of study would occur during facility siting studies in later phases. A cultural resources survey of all public property, including easements held by public entities, to be disturbed during construction is required by the Antiquities Code of Texas (Title 9, Chapter 191, Texas Natural Resources Code of 1977). Any sites located would be tested for significance and eligibility for the National Register. Disturbance of significant sites should be avoided to the extent possible.

3.38.4 Water Quality and Treatability [To be completed in subsequent phases of the study.]

3.38.5 Engineering and Costing For this alternative, surface water supply for the Mid-Cities area would be supplied from a treatment plant located near Lake Dunlap and delivered to existing water utilities in the service area. This alternative would augment the existing groundwater sources in the area by providing surface water on a wholesale basis to existing distribution companies. Figure 3.38-1 is a vicinity map showing possible. locations of a water treatment plant site and pipeline routes. For purposes of costing and general environmental assessment of this alternative, a surface water intake site was selected in the general vicinity of the south side of Lake Dunlap. From the intake, raw water would be pumped to a treatment plant located within two miles of the intake and from the treatment plant a pipeline would be constructed to supply water to existing distribution systems. Treatment would be conventional surface water treatment (Treatment Level 3, Table 3.0-4). The treatment costs estimated for this alternative are for typical conventional treatment of surface water of average quality and are used for relative evaluation of alternatives. Treatability studies of Canyon Lake water may find that less expensive treatment methods are appropriate. The major facilities required to implement this alternative are: Surface Water Intake and Pump Station Raw Water Pipeline to Treatment Plant

3-608 Water Treatment Plant (Level 3, Table 3.0-4, in Volume II) Finished Water Pump Station Transmission Pipeline Interconnects to Retail Water Utilities Elevated Storage Tank or Standpipe The system has been sized for delivery of year 2020 demands of 25,166 acft/yr (22.5 mgd, average day) with a maximum day to average day peaking factor of 2.2. Therefore, the intake, treatment plant, and finished water pump station are sized for 49.4 mgd through a 54-inch diameter transmission pipeline. The operating cost was determined for the total static lift of 180 feet and an annual delivery of 25,166 acft. Financing the project over 25 years at an 8.0 percent annual interest rate results in an annual expense of $5,870,000 (Table 3.38-4). The annual cost of water purchased from GBRA is $53/acft, for a payment of about $1,334,000 per year. Operation and maintenance costs, including power and purchase of stored water total $6,144,000. The annual costs, including debt repayment, interest, and operation and maintenance, total $12,014,000. For an annual delivery of 25,166 acft, the resulting annual cost of water is $477 per acfe7 (Table 3.38-4 ). This is the cost of treated water delivered on a wholesale basis and does not include the operating cost of the distribution system. The cost to mitigate for hydro generation lost to subordination, if any, is not included and will depend on the amount and owner of the subordinated right.

3.38.6 Implementation Issues

Requirements Specific to Amending the Canyon Lake Permit

1. If this alternative requires exceeding the current permitted average annual diversion from Canyon Lake of 50,000 acft, then a permit amendment will require: a. Application to the TNRCC b. Hydrologic studies substantiating requested firm yield. c. Environmental studies of in-stream flow and bay/estuary effects. d. Subordination of hydropower rights. e. Management of Edwards Aquifer by a regional agency to achieve the modeled aquifer pumpage/springflow scenario.

37 Costs for supply systems in the GBRA planning areas, which have capacity to meet peak demands, are typically higher when compared to alternatives in Volume 2, which are mostly larger projects with uniform annual delivery rates.

3-609 Table 3.38-4 Cost Estimate Summaries for Mid-Cities (IH-35 and Highway 78) Water Supply (G-26) (Third Quarter - 1994 Prices)

Item Alt G-26 Costs Capital Costs Intake and Treatment Plant $27,910,000 Transmission Pipelines 14,840,000 Interconnects to Existing Systems 2.200.000 Total Capital Cost $44,950,000 Engineering, Contingencies, and Legal Costs 14,870,000 Land Acquisition 200,000 Environmental Studies and Mitigation 240,000 Interest During Construction 2.410.000 Total Project Cost $62,670,000 Annual Costs Annual Debt Service $5,870,000 Annual Operation and Maintenance 3,970,000 Purchase of Stored Water 1,334,000 Annual Power Cost 840.000 Total Annual Cost $12,014,000 Annual Water Delivery (acftjyr) 25,166 Annual Cost of Water 1 $477/acft

Note: The cost to mitigate for hydro generation lost to subordination. if any, is not included and will depend on the amount and owner of the subordinated right.

3-610 Requirements Specific to Treatment and Distribution

1. Necessary permits: a. U.S. Army Corps of Engineers Sections 10 and 404 dredge and fill permits for stream crossings. b. TNRCC Discharge Permit for settling basin supernatant. c. GLO Sand and Gravel Removal permits. d. TPWD Sand, Gravel, and Marl permit for river crossings. e. Coastal Coordinating Council review may be required. 2. Right-of-way and easement acquisition. 3. Crossings: a. Highways and railroads b. Creeks and rivers c. Other utilities 4. Financing: a. Sponsoring entity must be identified and be able to incur debt to finance project. b. Participating entities must negotiate water purchase contracts with GBRA and establish rate structures.

3-611 THIS PAGE INTENTIONALLY LEFT BLANK.

3-612 3.39 Lower Guadalupe River Basin Water Requirements 3.39.1 Description of Area with Projections of Population and Water Demand The Lower Guadalupe River Basin Area as included here includes all of Gonzales, DeWitt, Victoria, Calhoun, and Refugio Counties (Figure 3.39-1). Gonzales county has been supplied from both groundwater and surface water sources (37 percent groundwater and 62 percent surface water in 1990). DeWitt County water use in 1990 was 69 percent groundwater and 31 percent surface water. The Victoria County area has relied upon groundwater from the Gulf Coast Aquifer, with industries of Victoria using surface water from the Guadalupe River. Due to declining water tables and the threat of salt water intrusion and subsidence in local areas of high pumpage, Victoria County water users are considering use of Guadalupe River water to meet a part of their future needs. In the case of Calhoun County, which is located along the Gulf Coast where aquifers tend to be quite saline, water supplies are now being obtained from the Guadalupe River and from Lake Texana of the Lavaca-Navidad River Basin. With the exception of livestock water from local surface sources (stock tanks and streams), water supplies for Refugio County are obtained from local aquifers. The purposes of the following discussion are to present the Texas Water Development Board high case population and water demand, with conservation, projections for these Lower Guadalupe River Basin counties. The projections are for information purposes, and are without reference to any particular plan of development, as has been done for other subareas of the Basin. The population of Gonzales County in 1990 was 17,205, with projections to 2050 of 19,897 (Table 3.39-1). Water use in Gonzales County in 1990 was 12,366 acft, of which 4,660 acft or 38 percent was groundwater. Projected water demand in the county in 2050 is 13,839 acft/yr (Table 3.39-1). According to Texas Water Development Board estimates, the dependable groundwater supply of Gonzales County is 45,560 acft/yr, which is significantly greater than projected water demands of the county. However, it is noted that there are potential problems with water quality which may affect the uses to which some of this water may be put. De Witt County's population in 1990 was 18,840 and is projected to increase to 22,608 in 2050 (Table 3.39-1). In 1990, water use in DeWitt County was 5,901 acft, of which 4,170

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legend Lower Guadalupe ~ River Basin Area -- Basin Divide TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA LOWER GUADALUPE RIVER BASIN AREA OI:I::::II:::JIOMII:::JI1Oo;;;;;;;;;;;;;;;;;;;;;;;;;;io20. Miles Scale HDR Engineering, Inc. FIGURE 3.39-1 Table 3.39-1 Population and Water Demand Projections 1 Lower Guadalupe Basin Area

Projection Date 1990 Area/Projection Actual 2000 1 2010 1 2020 1 2030 1 2040 1 2050

Population Gonzales County 17,205 18,023 18,603 18,883 19,179 19,538 19,897 Gonzales 6,527 7,120 7,414 7,556 7,707 7,889 8,071 Nixon 1,995 2,167 2,258 2,302 2,349 2,405 2,461 Rural 8,683 8,736 8,931 9,025 9,123 9,244 9,365

DeWitt County 18,840 19,485 20,040 20,553 21,276 21,942 22,608 Cuero 6,700 6,902 7,073 7,231 7,454 7,659 7,864 Yoakum 2,154 2,417 2,524 2,623 2,762 2,890 3,018 Yorktown 2,207 2,339 2,453 2,560 2,709 2,847 2,958 Rural 7,779 7,827 7,990 8,139 8,351 8,546 8,741

Victoria County 74,361 87,180 100,334 110,685 118,748 127,172 135,596 Victoria 55,076 65,250 75,679 83,885 90,278 96,956 103,634 Bloomington 1,888 2,640 3,121 3,623 4,171 4,590 5,009 Rural (Lavaca-Guadalupe Basin) 9,568 10,610 11,844 12,747 13,364 14,094 14,824 Rural (Guadalupe Basin) 7,829 8,680 9,690 10,430 10,935 11,532 12,129

Calhoun County 19,053 22,548 26,493 29,832 32,633 34,827 37,021 Point Comfort 956 1,120 1,239 1,340 1,425 1,491 1,557 Port Lavaca 10,886 12,387 14,235 15,799 17,111 18,138 19,165 Seadrift 1,277 1,695 2,105 2,535 2,858 3,110 3,362 Rural 5,934 7,346 8,914 10,158 11,239 12,088 12,937

Refugio County 7,976 7,939 8,415 8,780 9,096 9,278 9,460 Refugio 3,158 3,139 3,389 3,582 3,748 3,844 3,940 Woodsboro 1,731 1,723 1,820 1,893 1,957 1,993 2,029 Rural 3,087 3,077 3,206 3,305 3,391 3,441 3,491

Water Demands (adtLY!) Gonzales County Municipal 3,832 4,075 4,033 3,918 3,916 3,924 3,932 Gonzales Municipal 1,646 1,810 1,810 1,769 1,778 1,794 1,810 Nixon Municipal 373 398 395 384 384 385 386 Rural Municipal 1,813 1,867 1,828 1,765 1,754 1,745 1,736 Industrial 865 1,303 1,584 1,921 2,309 2,717 3,125 Steam-Electric Power 0 0 0 0 0 0 0 Irrigation 3,540 2,310 2,310 2,310 2,310 2,310 2,310 Mining 21 41 37 33 29 29 29 Livestock 4,108 4,443 4,443 4,443 4,443 4,443 4,443 Total Gonzales County 12,366 12,172 12,407 12,625 13,007 13,423 13,839

3-615 Table 3.39-1 (continued) Population and Water Demand Projections 1 Lower Guadalupe Basin Area Projection Date 1990 Area/Projection Actual 2000 1 2010 1 2020 1 20301 20401 2050

Water Demands (acftLY!l De Witt County Municipal 3,556 3,699 3,646 3,562 3,614 3,654 3,697 Cuero Municipal 1,716 1,678 1,656 1,620 1,645 1,664 1,683 Yoakum Municipal 425 406 404 400 411 421 431 Yorktown Municipal 405 440 440 439 455 469 483 Rural Municipal 1,010 1,175 1,146 1,103 1,103 1,100 1,100 Industrial 91 139 181 228 282 326 370 Steam-Electric Power 0 0 0 0 0 0 0 Irrigation 285 3,250 3,250 3,250 3,250 3,250 3,250 Mining 129 148 120 95 67 53 39 Livestock 1.840 2.432 2,432 2.432 2.432 2.432 2.432 Total DeWitt County 5,901 9,668 9,629 9,567 9,645 9,715 9,788

Victoria County Municipal 11,545 14,851 16,400 17,327 18,326 19,316 20,306 Victoria Municipal 9,152 11,548 12,885 13,719 14,562 15,422 16,282 Bloomington Municipal 181 370 413 455 514 555 596 Rural (Lav.-Guad. Basin) Mun. 1,217 1,613 1,706 1,734 1,787 1,836 1,885 Rural (Guadalupe Basin) Mun. 995 1,320 1,396 1,419 1,463 1,503 1,543 Industrial 20,032 37,974 49,097 61,388 71,794 83,891 95,988 Steam-Electric Power 2 887 26,000 26,000 31,000 31,000 31,000 31,000 Irrigation 13,699 12,172 10,800 10,350 9,900 9,450 9,000 Mining 2,409 2,314 2,088 1,090 2,207 2,424 2,641 Livestock 1,271 1.623 1.623 1,623 1.623 1.623 1.623 Total Victoria County 49,843 94,334 106,008 123,778 134,850 147,704 160,558

Calhoun County Municipal 3,916 4,022 4,497 4,849 5,221 5,500 5,779 Point Comfort Municipal 137 153 160 165 171 175 179 Port Lavaca Municipal 1,507 1,873 2,025 2,141 2,262 2,357 2,452 Seadrift Municipal 169 237 278 318 352 376 400 Rural Municipal 2,103 1,759 2,034 2,225 2,436 2,592 2,748 Industrial 3 24,539 36,797 46,656 57,654 67,434 78,009 88,584 Steam-Electric Power 62 200 200 200 200 200 200 Irrigation 35,421 22,750 22,050 22,050 20,475 20,475 20,475 Mining 1 35 34 20 9 4 2 Livestock 291 649 649 649 649 649 649 Total Calhoun County 3 64,230 64,453 74,086 85,422 93,988 104,837 115,689

3-616 Table 3.39-1 (continued) Population and Water Demand Projections 1 Lower Guadalupe Basin Area

Projection Date 1990 Area/Projection Actual 20001 20101 2020 1 2030 1 2040 1 2050

Water Demands (acftLTI) Refugio County Municipal 1,227 1,359 1,372 1,363 1,382 1,380 1,378 Refugio Municipal 569 566 581 586 600 603 606 Woodsboro Municipal 309 334 338 337 342 342 342 Rural Municipal 349 459 453 440 440 435 430 Industrial 0 0 0 0 0 0 0 Steam-Electric Power 0 0 0 0 0 0 0 Irrigation 0 83 83 83 83 83 83 Mining 77 28 14 7 4 1 0 Livestock 563 673 673 673 673 673 673 Total Refugio County 1,867 2,143 2,142 2,126 2,142 2,137 2,134

Groundwater Supplies Gonzales County 45,560 45,560 45,560 45,560 45,560 45,560 45,560 DeWitt County 15,866 15,866 15,866 15,866 15,866 15,866 15,866 Victoria County 41,130 41,130 41,130 41,130 41,130 41,130 41,130 Calhoun County 2,940 2,940 2,940 2,940 2,940 2,940 2,940 Refugio County 7,768 7,768 7,768 7,768 7,768 7,768 7,768

1 Texas Water Development Board, high case, with conservation. 2 Note: Projections include rights to use run-of-the-river flows for existing steam-electric power generation plant located at Victoria, which may not be continued in its existing condition. 3 A part of the projected water demands of Calhoun County will be met with water supplied from Lake Texana of the Lavaca Basin; i.e.; Formosa Plastics located in Calhoun County has purchased 30,000 acft of Lake Texana water and a pipeline has been constructed to deliver the water. Thus, the industrial water demand projections have been adjusted downward by this quantity, since Guadalupe Basin water will not be needed to meet these demands. It is further noted that new industrial water demand projections by TWDB for Calhoun County are expected to be somewhat lower than those shown here.

3-617 acft or 70 percent was groundwater. Projected water demands in DeWitt County in 2050 are 9,785 acft/yr (Table 3.39-1). Texas Water Development Board estimates of dependable groundwater supplies of De Witt County are 15,866 acft annually, which is greater than projected water demands for the County. In 1990, the population of Victoria County was 74,361, and is projected to increase to 135,596 in 2050 (Table 3.39-1). Water use in the county in 1990 was 49,843 acft, of which 29,222 acft was groundwater. Projected water demand in 2050 is 160,558 acft (Table 3.39-1). According to Texas Water Development Board estimates, the dependable groundwater supply of Victoria County is 41,130 acft/yr. Given these data, it is projected that with full development of groundwater, the 2050 demand for surface water would be 119,428 acft/yr. The population of Calhoun County in 1990 was 19,053, with projections to 2050 of 37,021 (Table 3.39-1). Water use in Calhoun County in 1990 was 64,230 acft with 59,681 acft or 92 percent being surface water (Table 3.39-1). Projected 2050 water demands are 152,189 acft/yr, with 125,084 acft being for industrial purposes (Table 3.39-1 ). Since the county has only 2,940 acft of dependable groundwater supplies, according to data from the Texas Water Development Board, Calhoun County will be forced to continue to depend upon surface water to meet its projected future needs. In this regard, Formosa Plastics of Calhoun County has purchased 30,000 acft of Lake Texana Water. Lake Texana is located in the neighboring Lavaca River Basin. The population of Refugio County in 1990 was 7,976, and is projected to increase to 9,460 in 2050 (Table 3.39-1). Water use in Refugio County in 1990 was 1,867 acft of which 1,360 acft or 73 percent was groundwater. Projected water demands in the county in 2050 are 2,134 acft annually (Table 3.39-1). Texas Water Development Board estimates of dependable groundwater supplies of Refugio County are 7, 768 acft, which exceeds projected demands to the year 2050.

3-618 3.40 GUADALUPE RIVER DIVERSION NEAR LAKE DUNLAP WITH TRANSFER OF DOWNSTREAM RIGHTS (G-27) 3.40.1 Description of Alternative This alternative includes a component of a comprehensive water management plan proposed by the San Antonio Water System38 (SAWS plan) involving several interrelated water supply and demand management elements which affect the availability and movement of water in both the Edwards Aquifer (including both pumpage and springflows) and throughout the Guadalupe - San Antonio River Basin. This component of the plan involves the diversion of Guadalupe River water near Lake Dunlap. Water potentially available under this alternative would originate from several sources and be delivered to the proposed North Water Treatment Plant in the San Antonio metropolitan area. Water potentially available includes: stored water from Canyon Lake, possible run-of-river water rights and stored water currently used at the Central Power & Light (CP&L) Coleta Creek steam electric power generating station, and possible run-of-river water rights currently used by GBRA and others at GBRA's Saltwater Barrier near Tivoli, Texas. Some of these water sources have been studied on a stand-alone basis in previous sections in Volume 2, however, this alternative considers combined quantities of water possibly available from several sources. Previous studies which are contained in Volume 2 considered water availability from stand alone sources and are briefly summarized herein. Section 3.17 describes the availability of unappropriated water at various points in the Guadalupe Basin, including at Lake Dunlap, and found that no firm yield exists from unappropriated flows without some kind of storage facility. Section 3.19 presents an alternative to divert unappropriated streamflow at Lake Dunlap and includes analysis of an off-channel storage facility which would create a small firm yield for the project. Section 3.20 contains studies of the purchase of 10,000 to 15,000 acft/yr of uncommitted stored water in Canyon Lake released to Lake Dunlap for diversion to the study area. Section 3.23 presents a study of McFaddin Reservoir, a proposed off-channel reservoir located near the Guadalupe - San Antonio river confluence, which might potentially be supplied by using senior water rights held by GBRA

"Proposed Water Resource Plan prepared by the San Antonio Water System and presented to the San Antonio Mayor's 2050 Water Resources Committee, April27, 1994. The SAWS plan is summarized in Appendix F.

3-619 and others associated with GBRA's Calhoun Canal Division. Further work performed to estimate water availability with the SAWS plan is described in Appendices G and H. Appendix G contains a description of studies made of Canyon Lake firm yield for possible changes in degree of hydropower subordination and/or aquifer management. Appendix H contains a description of analyses using the Guadalupe - San Antonio River Basin Model39 (GSA Model) to estimate firm water availability with the SAWS plan. For this alternative (G-27), a program of combined water rights (i.e., stored water from Canyon Lake and transferred senior water rights) is studied for availability to meet peak summer demands of those served by SAWS. The major facilities needed for this alternative include a surface water intake structure and pump station at Lake Dunlap on the Guadalupe River, water transmission pipeline, and treatment plant. A possible location of the facilities is shown on Figure 3.40-1.

3.40.2 Available Yield Water potentially available for diversion at Lake Dunlap for this alternative includes purchase of stored water from Canyon Lake (either uncommitted yield or by purchase (or transfer) of CP&L's existing contract for stored Canyon Lake water for make-up water for Coleto Creek Reservoir) and the use of senior downstream rights (i.e., rights senior in time to Canyon Lake) held by either CP&L for make-up water for Coleto Creek Reservoir or by GBRA and others associated with the Calhoun Canal Division.

39HDR Engineering, Inc., "Guadalupe-San Antonio River Basin Recharge Enhancement Study," Volumes I, II, and III, Edwards Underground Water District, September, 1993.

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\~//,,, ' ' __ ,, ... ,_ ' ' --

3-622 Table 3.40-1 Canyon Lake Firm Yield Available for Diversion at Lake Dunlap Total Uncommitted Firm yield Firm Yield 1 Aquifer Demand Hydropower at Lake Dunlap at Lake Dunlap Scenario 3 Scenario 2 (acft/yr) (acft/yr) 200,000 acft/yr 365 cfs 59,600 21,200 0 cfs 88,000 49,600 368,000 acft/yr 365 cfs 46,900 8,500 0 cfs 82,200 43,800 400,000 acft/yr 365 cfs 45,000 6,600 0 cfs 81,500 43,100 Notes: 1 Uncommitted firm yield is the portion of the total firm yield of Canyon Lake which has not been contractually committed. Existing contracts total 38,438 acft/yr assuming an average of 6,000 acft/yr delivered to CP&L at Cole to Creek Reservoir. 2 Hydropower scenario represents the required flowrate for power generation at Lake Dunlap. 3 The results of the simulated springflows from the TWDB Edwards Aquifer Model for all pumpage scenarios were adjusted to account for the difference in the model's simulated historical springflows and observed springflows.

Table 3.40-1 shows that with a demand on the Edwards Aquifer of 200,000 acft/yr the uncommitted firm yield of Canyon Lake (at Lake Dunlap) would be 21,200 acft/yr with a hydropower requirement of 365 cfs. If hydropower requirements were reduced to 0 cfs, the uncommitted firm yield could be increased to 49,600 acft/yr. This represents a potential 28,400 acft/yr increase in the total firm yield of Canyon Lake. Table 3.40-1 also shows that with demands on the Edwards Aquifer of 368,000 acft/yr and 400,000 acft/yr, the uncommitted firm yield of Canyon Lake (at Lake Dunlap) would be 8,500 acft/yr and 6,600 acft/yr respectively, with a hydropower requirement of 365 cfs. If hydropower requirements were reduced to 0 cfs, the uncommitted firm yield could be increased to about 43,000 acft/yr for either aquifer pumpage scenario.

Transfer of Downstream Rights At the point of diversion for the Calhoun Canal System which is located at the Saltwater Barrier just a few thousand feet downstream of the confluence of the San Antonio

3-623 and Guadalupe Rivers, GBRA holds interests in six water rights permits (Certificate of Adjudication Nos-. 18-5173, 18-5174, 18-5175, 18-5176, 18-5177, and 18-5178). These six permits have diversion rights totalling about 172,500 acft/yr, and are all senior to Canyon Lake. Of these senior rights, it was estimated for planning purposes that up to 40,000 acft/yr could be made available for long-term in basin and/or out-of-basin use and

40 additional quantities could potentially be made available for short-term or temporary use • At the Coleto Creek Project, CP&L presently has 20,000 acft/yr of run-of-the-river diversion rights from the Guadalupe River plus a contract with GBRA averaging 6,000 acft/yr for stored Canyon Lake water, both of which provide make-up water for cooling purposes at Coleto Creek Reservoir. To allow the possible transfer of CP&L's combined Coleto Creek rights from the Guadalupe River and Canyon Lake, potential shortfalls in cooling water needs could potentially be mitigated with SAWS reclaimed water diverted from the San Antonio River. Under this concept a new intake would be constructed at a diversion point near Goliad on the San Antonio River and a new 6.5 mile pipeline constructed to Coleto Creek Reservoir (see Section 3.42, for a more thorough discussion of reclaimed flows available to mitigate transferred water). Two combinations of potential water transfers were studied: (1) The GBRA/CP&L contract averaging 6,000 acft/yr of stored Canyon Lake water, together with the CP&L Coleto Creek run-of-the-river right from the Guadalupe River of 20,000 acft/yr;

(2) Both quantities in (1) plus 40,000 acft/yr from the GBRA Calhoun Canal Division rights.

The GSA Model was applied to compute firm water availability at Lake Dunlap from diversions under downstream senior water rights combined with a range of stored water allocations from Canyon Lake. Table 3.40-2 summarizes firm availability at Lake Dunlap with use of downstream water rights. Firm availability estimates were made both with and without application of the Trans-Texas Environmental Criteria for Instream Flows. As flows past the Saltwater Barrier were essentially unaffected by diversion under existing rights,

'"Memo from GBRA to HDR, 4/18/94.

3-624 Table 3.40-2 Firm Availability at Lake Dunlap with Selected Water Rights Transfers 1

Firm Availability at Lake Dunlap with Water Rights Transfers Portion of Canyon (acft/yr) Lake Yield Made Trans-Texas Available by GBRA to CP&L and Environmental Firm-Up Other Water 40,000 Acft/Yr Criteria Applied (acft/yr) CP&L' GBRA CCD Rights

0 8,157 8,157

Yes 10,000 18,157 18,405

20,000 28,157 28,780

40,599 Max 4 48,756 49,785

0 8,157 14,703

No 10,000 18,157 33,657

20,000 28,157 49,680

40,599 Max 4 48,756 78,600 1 Representative of 116 month drought period beginning July, 1947, and ending February, 1957. 2 Includes both GBRA Canyon Lake contract and CP&L run-of-the-river rights. 3 For other assumptions used in model runs refer to Appendix H. 4 Maximum uncommitted firm yield made available by GBRA from Canyon Lake assuming SAWS return flows are fully utilized thereby reducing Canyon Lake firm yield from 43,800 acft/yr to 40,599 acft/yr. consideration of Trans-Texas Environmental Criteria for freshwater inflows to bays and estuaries was unnecessary. Water transferred under GBRA Calhoun Canal Division (CCD) rights was made firm to the extent possible by a range of allocations from the presently uncommitted firm yield of Canyon Lake both subject to and independent of Trans-Texas Environmental Criteria. All estimates of firm availability assume that the Canyon Lake firm yield created by the conversion of the CP&L run-of-the-river rights and GBRA contract for Coleta Creek Reservoir makeup water would be allocated to firm-up available run-of-the-river water. Upon review of Table 3.40-2, it is clear that if Trans-Texas Environmental Criteria for Instream Flows were applied, firm availability would be limited to little more than the Canyon Lake firm yield made available by GBRA and the CP&L transfers. Without these

3-625 environmental criteria, however, firm availability of up to 78,600 acft/yr could be achieved with diversion of 40,000 acft/yr of GBRA CCD rights. Hence, 75 percent of the CCD water could be made available on a firm basis at Lake Dunlap. For environmental analysis and costing of this alternative, the firm availability analyzed includes the transfer or sale of 40,000 acft/yr of GBRA CCD water, all of CP&L's Coleta Creek rights, and a maximum of 40,599 acft/yr of stored water being made available by GBRA from Canyon Lake. The resulting combined firm availability is 78,600 acft/yr without the application of the Trans-Texas Environmental Criteria for Instrearn Flows. For information and comparative purposes, a cost estimate has also been prepared for facilities sized for delivery of the firm availability of 49,785 acft/yr based on application of the Trans Texas Environmental Criteria to the transfer or sale of 40,000 acft/yr of GBRA CCD water. Monthly median strearnflows and annual strearnflows averaged by decile below Canyon Lake, at Lake Dunlap, and at the Saltwater Barrier, are presented in Figures 3.40-2 and 3.40-3 for both existing conditions and with the diversion of the full 78,600 acft/yr of water made available under this alternative. Also shown in Figure 3.40-2 is the Trans-Texas desired monthly instrearn flow applicable below Lake Dunlap.

3.40.3 Environmental Issues Alternative G-27, would divert water from the Guadalupe River at Lake Dunlap and be conveyed by pipeline to a treatment plant in the north San Antonio metro area (Figure 3.40-1). This alternative employs a portion of the same pipeline route as the Guadalupe River alternatives (G-13, G-14, and G-15) discussed in Volume 2. Lake Dunlap is impounded by a small hydroelectric gated overflow darn on the Guadalupe River below New Braunfels and the confluence of the Carnal River. Lake Dunlap is a long, moderately deep lake filling the Guadalupe River channel. The water

41 exhibits alkaline to near neutral pH and high alkalinity • The land use and habitat in the project area reflect its location at the confluence of the Blackland Prairies with the Central Texas Plateau ecoregions (Figures 3.40-1) and the

41 Lockett, C.L. 1976. Classification of seventeen central Texas reservoirs. Master's Thesis. Southwest Texas State University.

3-626 GUADAUJPE RIVER BELOW CANYON DAM GUADAUJPE RIVER BELOW CANYON DAM """" 1.000.000 i~ ,. ... 000,000 -- - i< ...... ~ ...... l ...... ~ ~ ...000 ......

~ f-= ...... ~ w~ :a """" ...... :0 ,. ... r- - r- - - i ~ j!: ~ ,.i! .... ' -100,1100

~~ 1~ ~ 1 JN4 I FEB I MAR I APA I MAY I .AJN I JlA. 1 JlLJll ...... -· 00-0.10% 11-20% I 21-acni IJl[lil 31...0" I 41~ I OHIO%- I 01-70% I 71~ I 11-80% I 11·1tllni MONTHS STREAMFLDW DEal.ES

GUADALUPE RIVER AT LAKE DUNLAP GUADALUPE RIVER AT LAKE DUNLAP """" 1,000,1100 ~-- -- ,...... ----- i< 100,000 I - r- r- ~ "'""" l ""'·"" ----·------~ ..... ~ ...... f'.._ - ~ ...... ' ...... ~ ~ I - ~ ...... C= r- w w~ """" ...... ,. 10,000 i ~ .... ~ ~ -100.000 .AliA ..., .M.N I FEB I MAR y- ...... !.1-MI'II. 1'1:1...,"' •1-7n'lll. ,_ ,_ IU.1IIMI. ·- -· """ """ :0 Ill~~ ...... MONTHS STREAMFLOIN DECILES

TRANS TEXAS WATER PROGRAM I LEGEND: WEST CENTRAL STUDY AREA • WITH PROJECT

0 WITHOUT PROJECT CHANGES IN STREAMFLOW -GUADALUPE RIVER --TRANS-TEXAS ENVIRONMENTAL CRITERIA WITH DIVERSIONS AT LAKE DUNLAP (PLOTTED FOR POINT OF DIVERSION ONLY) lil~ ALTERNATIVE G-27 HDR Engineering, Inc. FIGURE 3.40-2 GUADALUPE RIVER AT SALTWATER BARRIER GUADALUPE RIVER AT SALTWATER BARRIER

'"'""" ~ -~~- ,-~- ~~~.------4,000,000 ·--~- ~~-~ ~ 110,000 f------r-----

---- ~ ~~- --~ """ i 100.000 i< .....

~------~ 00,000 s.ooo.ooo i 00,000 -~ I ...... -~- li! 70,000 ~ ~ 00,000 ~000,000 ~ 10,000 I 1,!00,000 ~--- I "'""" w !il "'""" 1,000,000 I ...... ;~ "'"""10,000 - ...... IUV .... JlL ~.... OCT IEC ~~htO- {I ...... - n.- ...... •t-1DMI. IIONTHS - - STREAMFLOW DECIL£S

TRANS TEXAS WATER PROGRAM I LEGEND: WEST CENTRAL STUDY AREA • WITH PROJECT 0 WITHOUT PROJECT CHANGES IN STREAMFLOW· GUADALUPE RIVER AT SALTWATER BARRIER WITH DIVERSIONS AT 1-il~ LAKE DUNLAP • ALTERNATIVE G-27 HDR Engineering, Inc. FIGURE 3.40-3 42 43 44 Blackland Prairie and Post Oak Savannah ' ' • The soils in the pipeline corridor range from light-colored, acid sandy loams (upland), dark-gray acid sandy loams and clays

45 (bottomland) to fairly uniform dark-colored calcareous clays • Climax grasses of the Post Oak Savannah are little bluestem, Indian grass, switch grass, purpletop, silver bluestem and Texas wintergrass. The overstory is primarily post oak and blackjack oak. The Blackland Prairies are characterized by these grasses as well as sideoats grama, hairy grama and tall dropseed. Post oak and blackjack oak are typically present as overstory, although only small

46 remnants of this upland woodland are generally present in this ecoregion • The northeastern third of the proposed pipeline corridor is primarily cropland (68 percent), grass, shrub, and brush (18 percent) with the remaining area a mixture of park,

47 8 49 woods (8 percent), urban (3 percent) and wetlands (3 percent) .4 ' • The majority of the project area is located in cropland. Impacts to terrestrial biological communities can generally be minimized or avoided by careful selection of the pipeline ROW. Less than 0.25 acres of riparian woods bordering the Lake Dunlap shore will be impacted during construction of the river intake structure. Lake Dunlap is used for boating, fishing and camping, so the intake structure should be as imperceptible as possible. The amounts of water that could be made available on a firm basis for diversion near Lake Dunlap under various Edwards pumping scenarios by releasing stored Canyon Lake water, plus diverting under selected downstream water rights, are shown in Tables 3.40-1

42 0mernik, James M. 1986. Ecoregions of the Conterminous United States. Annals of the Association of American Geographers, 77(1): pp. 118-125.

43Blair, W.F. 1950. The biotic provinces of Texas. Texas Journal of Science 2(1): pp. 93-117.

44Gould, F.W. 1975. The Grasses of Texas. Texas A&M University Press, College Station, Texas.

"Soil Conservation Service. 1977. Soil Survey of Guadalupe County, Texas. U.S. Department. Agriculture

46 Correl, D.S., and M.C. Johnston. 1979. Manual of the Vascular Plants of Texas. Texas Research Foundation, Renner, Texas.

47 McMahan, C.A., R.G. Frye, K.L. Brown. 1982. The Vegetation Types of Texas Including Cropland. Texas Parks and Wildlife Department, Austin, Texas.

48U .S. Fish and Wildlife Services. 1991. National Wetland Inventory Series. New Braunfels East, New Braunfels West, Schertz, Longhorn Quadrangles.

49USGS, 1990. NAPP Series. EROS Data Center, Sioux Falls, South Dakota.

3-629 and 3.40-2. The latter table also discloses the firm water available with and without application of the Trans-Texas criteria for instream flows and bay and estuary inflows to Alternative G-27. The Guadalupe River below Canyon Dam was the subject of an instrearn flow study during the mid 1980's, at the time a hydroelectric capability was installed, resulting in minimum flow requirements that were honored in developing this alternative. Because the water to be diverted at Lake Dunlap would consist of a dynamic mix of stored, firm water and run of river water, all of which is currently permitted, application of the Trans-Texas criteria will require additional clarification as to what water is subject to the criteria, and how (in a practical sense) they would be applied in this particular situation. At this time we can only say that monthly median flows resulting from meeting the Trans Texas criteria with Alternative G-27 would fall between the with and without project medians plotted in Figures 3.40-2 and 3.40-3. Figure 3.40-2 shows existing monthly median streamflows below Canyon Lake (period of record 1934-1989), and the changes anticipated to result from implementation of this alternative without the diversion limits imposed by the Trans-Texas criteria. While both positive and negative changes on the order of 10 to 20 percent are projected for late spring and summer (May-August), substantial decreases (25-50 percent) in monthly median streamflows are expected during the remainder of the year. These changes reflect the retention of water in Canyon Lake that would otherwise have been released to satisfy downstream hydroelectric generating needs, water rights and contracts (Table 3.40-2), coupled with the increase in summer releases for diversion at Lake Dunlap. Figure 3.40-2 shows how streamflows would be redistributed on an annual basis: during dry years, reductions in streamflow would average 5-15 percent in the lowest five deciles, while during

50 wetter years, streamflow could increase about 6 percent • Alterations in streamflow patterns of the magnitudes projected to occur in the reaches below Canyon Dam may result in changes in the average abundances of some aquatic populations, increase interannual variation, and reduce the overall carrying capacity in these reaches during dry years. Existing minimum streamflow requirements below Canyon Dam are expected to be adequate for at least minimal maintenance of the biological community in this reach, since flows during the critical summer period would be least

50HDR Engineering, Inc., 1994. Unpublished hydrologic model results. Austin, Texas.

3-630 affected. Although the peak summer recreational period would be relatively unaffected, river recreationalists would experience more, or more extended, low flow periods during the early spring and fall as a result of implementation of Alternative G-27. The potential impacts to river recreation and local economies should be examined in detail if this alternative is retained for further consideration. Projected changes in monthly median flows, and in annual average flows by decile, are presented for the Guadalupe River below the diversion point at Lake Dunlap and at the Saltwater Barrier in Figures 3.40-2 through 3.40-3. Below Lake Dunlap, substantial ( > 20 percent) reductions in monthly median streamflows could occur throughout the year, with the largest proportional impacts occurring during the driest years. At the Saltwater Barrier (San Antonio Bay inflows), monthly median streamflows would be reduced about 5-10 percent during late spring and summer (May-August), while both positive and negative changes of less than 5 percent would occur during the remaining months. Most of these reductions would occur during wet years, with dry year streamflows being largely unaffected (Figure 3.40-3). Below Lake Dunlap the substantial reductions in streamflows projected to occur during the driest years, particularly. during the historic summer (July-September) low flow period, may adversely affect some biological communities downstream. However, much of the river below IH 35 (70 of the 100 river miles between Lake Dunlap and Gonzales) consists of lentic habitats (impoundments) that would not necessarily experience adverse effects. Reductions in San Antonio Bay inflows would approach 10 percent of the monthly medians only during May and August, and would occur primarily during wet years. Instream flow studies should be conducted in the reaches below Canyon Dam and Lake Dunlap in order to evaluate potential impacts to the community as a whole, but more particularly to the aquatic species discussed below as being of concern to state and federal resource agencies. Because of the lack of effect on the lower flow ranges at the Saltwater Barrier, impacts to San Antonio Bay as a result of increased length or severity of drought periods do not appear to have great potential for being significant. For example, using a 1934-1989 period of record, the minimum annual flow would have increased from 52,289 to 57,389 acre feet as a result of implementing Alternative G-27. In the same simulation, 25th percentile and median flows at the Saltwater Barrier are shown to decrease by only 3.4 and

3-631 1.6 percent, respectively, with only rrunor variation m seasonal patterns. Since this alternative is a diversion, not an impoundment, its operation will have minimal effects on

51 flood flows • Although the Natural Heritage Program does not report any endangered or threatened species directly along the proposed pipeline corridor, some have been reported

2 in the viciniif • The areas of grasslands, brush, and shrub could be habitat for several endangered or threatened species, such as the Black-capped Vireo, Golden-cheeked Warbler, Texas horned lizard, and Texas garter snake (Appendix B, Tables 6 and 22, Volume 2). Surveys for the presence of protected species would be conducted within the proposed construction corridor where disturbance of potential habitat cannot be avoided. The Cagle's map turtle, Guadalupe bass, and the blue sucker ranges extend from the Edwards Plateau through the Blackland Prairie to the Coastal Plains in Guadalupe River. Cagle's map turtle has been located as far south as Victoria, Texas on the Coastal Plain. The Guadalupe bass may be found in Lake Dunlap. Streamflow is an important component of its habitat requirements. The Guadalupe bass, best adapted for flowing water, is often found in flowing water near riffles feeding on aquatic insects. Although the Guadalupe bass is found in reservoirs such as Canyon Lake, it may be at a competitive disadvantage

53 with other bass species in more lentic environments • The blue sucker, a large river fish, is a candidate for federal protection with probable occurrence in Guadalupe County, although the presence of several dams in this reach of the Guadalupe suggests that it may no longer be present. Cultural resources protection on public lands in Texas is afforded by the Antiquities Code of Texas (Title 9, Chapter 191, Texas Natural Resource Code of 1977), the National Historic Preservation Act (PL96-515), and the Archaeological and Historic Preservation Act

52TPWD. 1994. Unpublished data files and maps of the Natural Heritage Program. Resource Protection Division, Austin, Texas. TOES. 1992. Endangered, Threatened, and Watch List of Natural Communities of Texas, Publication 8, Austin, Texas; TOES. 1993. Endangered, Threatened, and Watch List of Texas Plants, Third Revision, Austin, Texas.

"Garrett, Gary P. 1991. Guidelines for the Management of Guadalupe Bass. Publication PWD-RP-N3200- 367-ll/91, Texas Parks and Wildlife Department, Austin, Texas.

3-632 (PL93-291 ). All areas to be disturbed during construction will be first surveyed by qualified professionals for the presence of significant cultural resources.

3.40.4 Water Quality and Treatability (To be completed in subsequent phases of the study.)

3.40.5 Engineering and Costing For this alternative, the combined firm water available at Lake Dunlap would be diverted through a new intake and pump station located along the shore of Lake Dunlap and pumped in a transmission line to the proposed North Water Treatment Plant. The diversion rate from the Guadalupe River would vary considerably from month to month with highest use in the summer months needed in order to keep SAWS aquifer pump age uniform throughout the year. The major facilities required to implement this alternative are: Reservoir Intake and Pump Station Raw Water Pipeline to Treatment Plant Raw Waterline Booster Pump Station Water Treatment Plant (Level 3, see Table 3.0-4, Volume 2) Finished Water Pump Station Distribution System Improvements The reservoir intake and pump station is sized to deliver a maximum monthly volume of 13,100 acft/month (141 mgd) through a 90 inch diameter pipeline. The operating cost was determined for the total raw water static lift of 425 feet and an annual water delivery of 78,600 acft/yr. Financing the project over 25 years at an 8.0 percent annual interest rate results in an annual expense of $25,060,000 (Table 3.40-3). The annual cost of water purchased from GBRA is $53 per acft, for an annual payment of $2,150,000. Purchase of water using senior water rights of the Calhoun Canal Division is estimated to cost $53 per acft for firm water (same cost as stored water from Canyon Lake). For purchase of 40,000 acft/yr using senior rights, firm availability is estimated to be 37,000 acft/yr at the Saltwater Barrier (see Section 3.23, Volume 2) for an annual cost of $1,960,000. Compensation for CP&L's contract for stored water from Canyon Lake is assumed to be $53 per acft/yr and is included in the annual cost for replacement water for make-up needs at CP&L's Coleta Creek Reservoir. Operation and maintenance costs, including power and purchase of all

3-633 Table 3.40-3 Cost Estimate for Guadalupe River Diversion Near Lake Dunlap with Transfer of Downstream Rights (G-27) (without Trans-Texas In-stream Environmental Criteria Applied to the Transferred Rights) (Third Quarter - 1994 Prices) Alternate G-27 Item Costs Capital Costs Intake and Pump Station $6,540,000 Transmission Pipeline and Pumping 41,970,000 Treatment Plant 56,240,000 Delivery System 1 91.240.000 Total Capital Cost $195,990,000 Engineering, Contingencies, and Legal Costs 57,650,000 Land Acquisition 170,000 Environmental Studies and Mitigation 170,000 Interest During Construction 13.480.000 Total Project Cost $267,460,000 Annual Costs Annual Debt Service $25,060,000 Annual Operation and Maintenance 10,200,000 Replacement Water Cost for Coleta Creek (Includes Makeup Water from SAWS Return Flows and Purchase of CP&L 1,140,000 GBRA Stored Water Contract) Purchase of 40,599 acft/yr Canyon Lake Stored Water 2,150,000 Purchase of 40,000 acft/yr under Senior Water Rights from Saltwater Barrier 1,960,000 Annual Power Cost 5.170.000 Total Annual Cost $45,680,000 Available Project Yield (acft/yr) 78,600 Annual Cost of Water $581/acft 1 As described in Section 3.0.2 delivery system improvement costs were determined from studies for delivery of Applewhite Reservoir water and may be lower for a water source on the northwest side of the city.

3-634 stored, transferred and replacement water, total $20,620,000. The total annual costs, including debt repayment, interest, operation and maintenance and all water purchases, total $45,680,000, for all facilities. Included in these costs are annual costs for facilities to deliver SAWS reclaimed water from the San Antonio River to replace CP&L's cooling water needs (including compensation for CP&L's Canyon Lake stored water contract) total $1,140,000 as described in Section 3.42.5. For an annual firm yield of 78,600 acft, the resulting annual cost of water developed under this aspect of the SAWS plan is $581 per acft (Table 3.40-3). An estimate has also been made of the cost to deliver the firm yield available at Lake Dunlap for the same transfers of water rights and stored water with application of the Trans-Texas environmental criteria (i.e. 49,785 acft/yr, Table 3.40-1). For this scenario, the reservoir intake and pump station is sized to deliver a maximum monthly volume of 9,800 acft/month (105 mgd) through a 78 inch diameter pipeline. The operating cost was determined for the total raw water static lift of 425 feet and an annual water delivery of 49,785 acft/yr. The total annual costs, including debt repayment, interest, operation and maintenance and all water purchases, total $36,790,000 (Table 3.40-4) for all facilities. For an annual firm yield of 49,785 acft, the resulting annual cost of water developed under this aspect of the SAWS plan is $739 per acft.

3.40.6 Implementation Issues An institutional arrangement is needed to implement projects including financing on a regional basis. Requirements Specific to Transfer of Downstream Rights

1. CP&L and GBRA diversion permits will need to be amended to change the point of diversion. CP&L run-of-the-river permit will need to be transferred.

2. Water to replace the CP&L contract for stored water and run-of-the-river rights, and possibly the GBRA Calhoun Canal rights need to be considered. Refer to Section 3.42 for more discussion of a potential alternative available for replacement water.

Requirements Specific to River Diversion and Transmission Pipeline:

1. Necessary permits: a. U.S. Army Corps of Engineers Sections 10 and 404 dredge and fill permits for stream crossings. b. GLO Sand and Gravel Removal permits.

3-635 Table 3.40-4 Cost Estimate for Guadalupe River Diversion Near Lake Dunlap with Transfer of Downstream Rights (G-27) (with Application of the Trans-Texas In-stream Environmental Criteria Applied to the Transferred Rights) (Third Quarter - 1994 Prices) Alternate G-27 Item Costs Capital Costs Intake and Pump Station $5,970,000 Transmission Pipeline and Pumping 36,990,000 Treatment Plant 41,970,000 Delivery System 1 73.220.000 Total Capital Cost $158,150,000 Engineering, Contingencies, and Legal Costs 46,420,000 Land Acquisition 170,000 Environmental Studies and Mitigation 170,000 Interest During Construction 10.900.000 Total Project Cost $215,810,000 Annual Costs Annual Debt Service $20,220,000 Annual Operation and Maintenance 7,980,000 Replacement Water Cost for Coleto Creek (Includes Makeup Water from SAWS Return Flows and Purchase of CP&L 1,140,000 GBRA Stored Water Contract) Purchase of 40,599 acft/yr Canyon Lake Stored Water 2,150,000 Purchase of 40,000 acft/yr under Senior Water Rights from Saltwater Barrier 1,960,000 Annual Power Cost 3.340.000 Total Annual Cost $36,790,000 Available Project Yield (acft/yr) 49,785 Annual Cost of Water $739/acft 1 As described in Section 3.0.2 delivery system improvement costs were determined from studies for delivery of Applewhite Reservoir water and may be lower for a water source on the northwest side of the city.

3-636 c. TPWD Sand, Gravel, and Marl permit for river crossings. d. Coastal Coordinating Council review may be required. 2. Right-of-way and easement acquisition. 3. Crossings. a. Highways and railroads b. Creeks and rivers c. Other Utilities

Requirements Specific to Treatment and Distribution

1. Detailed study needed of the cost of pumping and transrrusswn pipeline improvements necessary to effectively integrate the new supply into SAWS water supply system. 2. Study needed of cost to convey and distribute water to other area water utilities.

Requirements Specific to Amending the Canyon Lake Permit

3-637 THIS PAGE INTENTIONALLY LEFf BLANK.

3-638 3.41 GUADALUPE RIVER DIVERSION NEAR GONZALES WITH TRANSFER OF DOWNSTREAM RIGHTS (G-28) 3.41.1 Description of Alternative This alternative includes a component of a comprehensive water management plan proposed by the San Antonio Water System54 (SAWS plan) involving several interrelated water supply and demand management elements which affect the availability and movement of water in both the Edwards Aquifer (including both pumpage and springflows) and throughout the Guadalupe - San Antonio River Basin. This component of the plan involves the diversion of Guadalupe River water near Gonzales. Water potentially available under this alternative would originate from several sources and be delivered to the proposed North Water Treatment Plant in the San Antonio metropolitan area. Water potentially available includes: stored water from Canyon Lake, possible run-of-river water rights and stored water currently used at the Central Power & Light (CP&L) Coleto Creek steam-electric power generating station, and possible run-of-river water rights currently used by GBRA and others at the Saltwater Barrier. Some of these water sources have been studied on a stand alone basis in previous sections in Volume 2, however, this alternative considers combined quantities of water possibly available from several sources. Previous studies which are contained in Volume 2 considered water availability from stand alone sources and are briefly summarized herein. Section 3.17 describes the availability of unappropriated water at various points in the Guadalupe Basin, including at Gonzales, and found that no firm yield exists from unappropriated flows without some kind of storage facility. Section 3.23 presents a study of McFaddin Reservoir, a proposed off channel reservoir located near the Guadalupe - San Antonio river confluence, which might potentially be supplied by the using of senior water rights held by GBRA and others associated with GBRA's Calhoun Canal Division. Further work performed to estimate water availability with the SAWS plan is described in Appendices G and H. Appendix G contains a description of studies made of Canyon Lake firm yield for possible changes in degree of hydropower subordination and/or aquifer management. Appendix H contains a

3-639 description of analyses using the Guadalupe - San Antonio River Basin Model55 (GSA Model) to estimate firm water availability with the SAWS plan. For this alternative (G-28), a program of combined water rights (i.e .. stored water from Canyon Lake and transferred senior water rights) is studied for availability to meet peak summer demands of those served by SAWS. The major facilities needed for this alternative include a surface water intake structure and pump station near Gonzales on the Guadalupe River, water transmission pipeline, and treatment plant. A possible location of the facilities is shown on Figure 3.41-1.

3.41.2 Available Yield Water potentially available for diversion at Gonzales for this alternative includes purchase of stored water from Canyon Lake (either uncommitted yield or by purchase (or transfer) of CP&L's existing contract for stored Canyon Lake water for make-up water for Coleto Creek Reservoir) and the use of senior downstream rights (i.e., rights senior in time to Canyon Lake) held by either CP&L for make-up water for Coleto Creek Reservoir or by GBRA and others associated with the Calhoun Canal Division.

Canyon Lake Yield The firm yield of Canyon Lake is defined to be the maximum amount of water the lake could have supplied through the drought of record after allowing for passage of inflows when required for senior downstream water rights (i.e., water rights with priority dates senior to Canyon Lake). The drought of record for Canyon Lake covers a 116 month period of time which begins in July, 1947, and ends in February, 1957. Below Canyon Lake, there are senior water rights totaling more than 225,000 acft/yr (exclusive of hydropower rights) that require passage of lake inflows to meet their rights. Additionally, GBRA holds non consumptive hydropower rights for approximately 1,300 cfs below New Braunfels which are senior to Canyon Lake and the City of Seguin holds a senior non-consumptive hydroelectric right for 365 cfs. GBRA hydropower rights are currently subordinated to about 600 cfs. When river flows originating below Canyon Lake exceed the requirements of senior water

"HDR Engineering, Inc., "Guadalupe-San Antonio River Basin Recharge Enhancement Study," Volumes I, ll, and III, Edwards Underground Water District, September, 1993.

3-640 Central Texas Plateau Texas Black/and Prairies East Central Texas Plains N t

Texas Black/and Prairies NORTH WATER TREATMENT PLANT'\"'

Texas Plains

Legend TRANS TEXAS WATER PROGRAM I Basin Divide WEST CENTRAL STUDY AREA -- Possible Pipeline Route ~ Ecoregion 0 Water Treatment Plant GUADALUPE RIVER DIVERSION 1-i}~ NEAR GONZALES 0 10 20Miles ALTERNATIVE G-28 ~····-Scale HDR Engineering, Inc. FIGURE 3.41-1 rights including hydropower needs, int1ows to the lake can be stored for later release. Springflow from the Edwards Aquifer contributes substantially to the flow of the Guadalupe River and, consequently, provides water to meet a significant portion of downstream water rights, including GBRA and City of Seguin hydroelectric rights. If springflow is decreased, due to dry weather and/or aquifer pumpage, a greater proportion of downstream senior water rights must be met by passage of Canyon Lake inflows making less water available for storage. Because springflow and downstream hydroelectric rights have direct effect on the firm yield of Canyon Lake, firm yield has been estimated for several alternative scenarios of hydroelectric rights subordination and aquifer pumpage. Subordination of hydroelectric rights means that inflows to Canyon Lake are not subject to being released to meet a specified hydroelectric target flowrate downstream of Canyon. Canyon Lake inflows up to 90 cfs, 100 cfs, or 120 cfs depending on month of the year and drought conditions must be passed in accordance with the Federal Energy Regulatory Commission (FERC) requirements for hydroelectric facilities at Canyon Dam. FERC requirements at Canyon Dam were satisfied in all simulations using the GSA Model regardless of the degree of hydropower subordination downstream. The GSA Model has been modified and applied to compute the uncommitted firm yield of Canyon Lake (diverted at Gonzales) subject to two hydroelectric rights subordination scenarios and three aquifer pumpage scenarios for a total of six combined alternatives. The uncommitted firm yield is the portion of the total firm yield which is not presently allocated to satisfy existing contractual commitments. Table 3.41-1 contains a summary of the Canyon Lake estimated total firm yield and uncommitted firm yield available for diversion at Gonzales. Refer to Appendix G for a detailed presentation of GSA Model modifications and a complete summary of Canyon Lake firm yield analyses. Table 3.41-1 shows that with a demand on the Edwards Aquifer of 200,000 acft/yr the uncommitted firm yield of Canyon Lake (at Gonzales) would be 24,700 acft/yr with a hydropower requirement of 365 cfs. If hydropower requirements were reduced to 0 cfs, the uncommitted firm yield could be increased to 43,400 acft/yr. This represents a potential 18,700 acft/yr increase in the total firm yield of Canyon Lake.

3-642 Table 3.41-1 Canyon Lake Firm Yield Available for Diversion at Gonzales Total Uncommitted Firm yield Firm Yield 1 Aquifer Demand Hydropower at Gonzales at Gonzales Scenario Scenario 2 (acft/yr) (acft/yr) 200,000 acft/yr 365 cfs 63,100 24,700 0 cfs 81,700 43,300 368,000 acft/yr 365 cfs 46,500 8,100 0 cfs 76,800 38,400 400,000 acft/yr 365 cfs 44,500 6,100 0 cfs 76,200 37,800 Notes: 1 Uncommitted firm yield is the portion of the total fum yield of Canyon Lake which has not been contractually committed. Existing contracts total 38,438 acft/yr assuming an average of 6,000 acft/yr delivered to CP&L at Coleto Creek Reservoir. 2 Hydropower scenario represents the required flowrate for power generation at Lake Dunlap.

Table 3.41-1 also shows that with demands on the Edwards Aquifer of 368,000 acft/yr and 400,000 acft/yr, the uncommitted firm yield of Canyon Lake (at Gonzales) would be 8,100 acft/yr and 6,100 acft/yr respectively, with a hydropower requirement of 365 cfs. If hydropower requirements were reduced to 0 cfs, the uncommitted firm yield could be increased to about 38,000 acft/yr for either aquifer pumpage scenario.

Transfer of Downstream Rights At the point of diversion for the Calhoun Canal System which is located at the Saltwater Barrier just a few thousand feet downstream of the confluence of the San Antonio and Guadalupe Rivers, GBRA holds interests in six water rights permits (Certificate of Adjudication Nos. 18-5173, 18-5174, 18-5175, 18-5176, 18-5177, and 18-5178). These six permits have diversion rights totalling about 172,500 acft/yr, and are all senior to Canyon Lake. Of these senior rights, it was estimated for planning purposes that up to 40,000 acft/yr could be made available for long-term in basin and/or out-of-basin use and

3-643 56 additional quantities could potentially be made available for short-term or temporary use • At the Coleta Creek Project, CP&L presently has 20,000 acft/yr of run-of-the-river diversion rights from the Guadalupe River plus a contract with GBRA averaging 6,000 acft/yr for stored Canyon Lake water, both of which provide make-up water for cooling purposes at Coleta Creek Reservoir. To allow the possible transfer of CP&L's combined Coleta Creek rights from the Guadalupe River and Canyon Lake, potential shortfalls in cooling water needs could potentially be mitigated with SAWS reclaimed water diverted from the San Antonio River. Under this concept a new intake would be constructed at a diversion point near Goliad on the San Antonio River and a new 6.5 mile pipeline constructed to Coleta Creek Reservoir (see Section 3.42, for a more thorough discussion of reclaimed flows available to mitigate transferred water). Two combinations of potential rights transfers were studied: (1) The GBRA/CP&L contract averaging 6,000 acft/yr of stored Canyon Lake water, together with the CP&L Coleta Creek run-of-the-river right from the Guadalupe River of 20,000 acft/yr;

(2) Both quantities in (1) plus 40,000 acft/yr of GBRA Calhoun Canal Division water.

The GSA Model was applied to compute firm water availability at Gonzales from diversions under downstream senior water rights combined with a range of stored water allocations from Canyon Lake. Table 3.41-2 summarizes firm availability at Gonzales with use of downstream water rights. Firm availability estimates were made both with and without application of the Trans-Texas Environmental Criteria for Instream Flows. As flows past the Saltwater Barrier were essentially unaffected by diversion under existing rights, consideration of Trans-Texas Environmental Criteria for freshwater inflows to bays and estuaries was unnecessary. Water transferred under GBRA's Calhoun Canal Division (CCD) rights was made firm to the extent possible by a range of allocations from the presently uncommitted firm yield of Canyon Lake both subject to and independent of Trans-Texas Environmental Criteria. All estimates of firm availability assume that the Canyon Lake firm yield created by the conversion of the CP&L run-of-the-river rights and GBRA contract for Coleta

56Memo from GBRA to HDR, 4/18/94.

3-644 Table 3.41-2 Firm Availability near Gonzales with Selected Water Rights Transfers 1

Firm Availability near Gonzales with Water Rights Transfers Portion of Canyon (acft/yr) Lake Yield Made Trans-Texas Available by GBRA to CP&L and Environmental Firm-Up Other Water 40,000 Acft/Yr Criteria Applied (acft/yr) CP&L 2 GBRA CCD Rights

0 7,232 7,700

Yes 10,000 17,232 18,817

20,000 27,232 30,112

35,588 Max 4 42,820 46,718

0 7,232 13,954

No 10,000 17,232 33,343

20,000 27,232 47,359

35,588 Max 4 42,820 71,260

' Representative of 116 month drought period beginning July, 1947, and ending February. 1957. 2 Includes both GBRA Canyon Lake contract and CP&L run-of-the-river rights. 3 For other assumptions used in model runs refer to Appendix H. 4 Maximum uncommitted firm yield made available by GBRA from Canyon Lake assuming SAWS return flows are fully utilized thereby reducing Canyon Lake firm yield from 38,400 acft/yr to 35,588 acft/yr.

Creek Reservoir makeup water would be allocated to firm-up available run-of-the-river water. Upon review of Table 3.41-2, it is clear that if Trans-Texas Environmental Criteria for Instream Flows were applied, firm availability would be limited to little more than the Canyon Lake firm yield made available by GBRA and the CP&L transfers_ Without these environmental criteria, however, firm availability of up to 71,260 acft/yr could be achieved with diversion under 40,000 acft/yr of GBRA CCD rights. Hence, 71 percent of the rights transferred could be made available on a firm basis at Gonzales. For environmental analysis and costing of this alternative, the firm availability analyzed includes the transfer or sale of 40,000 acft/yr of GBRA CCD rights, all of CP&L's Coleta Creek rights, and a maximum of 35,588 acft/yr of stored water being made available

3-645 by GBRA from Canyon Lake. The resulting combined firm availability is 71,260 acft/yr without the application of the Trans-Texas Environmental Criteria for lnstream Flows. Monthly median streamflows and annual streamt1ows averaged by decile below Canyon Lake, at Gonzales, and at the Saltwater Barrier, are presented in Figures 3.41-2 and 3.41-3 for both existing conditions and with the diversion of the full 71,260 acft/yr of water made available under this alternative. Also shown in Figure 3.41-2 is the Trans-Texas desired monthly instream flow applicable below Gonzales.

3.41.3 Environmental Issues Alternative G-28, would divert water from the Guadalupe River near the City of Gonzales and convey the water in a pipeline to the proposed North Water Treatment Plant (Figure 3.41-1) in the San Antonio metro area. This alternative employs a portion of the same pipeline route in Bexar County as the Guadalupe River Diversion near Lake Dunlap (Alternative G-27) discussed in Section 3.40. The intake will be located below the confluence of the San Marcos River and the Guadalupe River in the Blackland Prairie ecoregion (Figure 3.41-1). The transmission pipeline would convey the water west along existing corridors into Guadalupe County. The

57 58 59 land use and habitat are typical of the Blackland Prairie ' ' • The proposed North Water Treatment Plant would be located in the Central Texas Plateau ecoregion (Figures

60 3.41-1 ) • The soils of the proposed pipeline corridor range from light-colored, acid sandy loams (upland), dark-gray acid sandy loams and clays (bottomland) to fairly uniform dark

61 colored calcareous clays • The Blackland Prairies are characterized by little bluestem, Indian grass, switch grass, purpletop, silver bluestem, Texas wintergrass as well as sideoats grama, hairy grama and tall dropseed. Post oak and blackjack oak are typically present as

570mernik, James M. 1986. Ecoregions of the Conterminous United States. Annals of the Association of American Geographers, 77(1): pp. 118-125.

"Blair, W.F. 1950. The biotic provinces of Texas. Texas Journal of Science 2(1): pp. 93-117.

"Gould, F.W. 1975. The Grasses of Texas. Texas A&M University Press, College Station, Texas.

(i()Omernik, James M. 1986. Ecoregions of the Conterminous United States. Annals of the Association of American Geographers, 77(1): pp. 118-125.

"Soil Conservation Service. 1978. General Soils Map Gonzales County, Texas. U.S. Department. Agriculture

3-646 GUADALUPE RIVER BELOW CANYON DAM GUADALUPE RIVER BELOW CANYON DAM

70,000 1,800,000 --

~ 1,400.000 --r-- . ~ .,.., « li: 1,200,000 ~ .. .., l 1- ~ 40.000 ~ .., ~ ... Iii 30,000 ~ 1100,000 ~ ,..., "' 5l eoo,ooo "~ I j!: 10,000 - ~ _til " •o ID 10 IU II_ ...... _ ~ 1 1 MAY - JU ..01 7f-80K 81-80% 11-100% MONTHS STREAMFLOW DEalES

GUADALUPE RIVER AT GONZALES GUADALUPE RIVER AT GONZALES

70.000 --~ 1,000.., ~ 1...... ~ .,.., « li: ~ 50,000 l1,200,000 1.000.., ~ 40,000 ~ ...,.., ~ :::-,.. Iii 30,000 - ~ ~ ,..., r-. "' 5l ~ -..,..., "~ ~ 10,000 ,...., ~ ::1 .n u.v .UN .IUO. AUO ocr NOV DEC M~ -t'!H-~ .-t.Mifll. .&t.AIW. .Ct.A'llll:. •t.7n

TRANS TEXAS WATER PROGRAM I LEGEND: WEST CENTRAL STUDY AREA • WITH PROJECT D WITHOUT PROJECT CHANGES IN STREAMFLOW -GUADALUPE RIVER --TRANS-TEXAS ENVIRONMENTAL CRITERIA WITH DIVERSIONS NEAR GONZALES AND WATER (FOR GUADALUPE RIVER AT CUERO GAGE) lil~ RIGHTS TRANSFERS ·ALTERNATIVE G-28 HDR Engineering, Inc. FIGURE 3.41-2 GUADALUPE RIVER AT SALTWATER BARRIER GUADALUPE RIVER AT SALTWATER BARRIER

4,000,000-, .. ----,------,---, ------121),000 ,---r------~

110,.000 j 3,500,000 ----0.--- t----i--+ - l--1----t--+--- . 11<>.000 1--- f------1--- -+--" --+--~ i ...... 10,000 70.000 ...... ! =~ : : • t-' T ...... !,....,,... II ., r I ...... l-f~l~ I ...... 1,000,000 +---t--+--t- ~ I ...... &oo,OOO ~ 10.000 •o ~ IJ.tO" l'f~ I 41 ..... ft«<% I lt-70% -, 71-eo% I 11-110% I 11-10Ho ...... IlL ...... OCT DEC ll1ill -- -· STREAMFLOW OECILES IIONTHS -

TRANS TEXAS WATER PROGRAM I LEGEND: WEST CENTRAL STUDY AREA

• WITH PROJECT CHANGES IN STREAMFLOW ·GUADALUPE RIVER D WITHOUT PROJECT AT SALT WATER BARRIER WITH DIVERSIONS AT Rl~ GONAZLES - ALTERNATIVE G-28 HDR Engineering, Inc. FIGURE 3A 1-3 overstory, although only small remnants of this upland woodland are generally present in 62 63 this ecoregion ' • The proposed North Water Treatment Plant near San Antonio is in the remnant areas of brush, shrub and grassland in northern Bexar County just west of Cibolo Creek64• On the eastern edge of the Balcones Escarpment, this rapidly urbanizing area is on the Spanish King's Highway, the Camino Real. Comanche Lookout, a new City of San Antonio Park is located in the general vicinity. This 58 acre park contains sites of prehistoric,

65 colonial and modern human activities • Stream crossings in the proposed corridor are mostly intermittent. Major stream crossings include the Guadalupe River near Seguin and Cibolo Creek, lower perennial stream. Numerous impounded ponds for stock and other agricultural uses dot the Blackland Prairie. Depending on the final alignment, the transmission line may cross the Guadalupe River at Seguin. However, the transmission line corridor is conceptual at this phase of the study and exact impacts can not be determined with out further study. The pipeline corridor is mostly improved pasture and cropland (60 percent), grass and brush (26 percent) with the remaining area a mixture of park, woods (8 percent), urban

66 67 (2 percent) and wetlands ( 4 percent) ' • The majority of the project area is located in cropland. Terrestrial impacts can generally be minimized or avoided by careful selection of the pipeline ROW. Less than 0.25 acres of riparian woods bordering the Guadalupe River shore will be impacted during construction of the river intake structure.

62 0mernik, James M. 1986. Ecoregions of the Conterminous United States. Annals of the Association of American Geographers, 77(1): pp. 118-125.

63 Correl, D.S., and M.C. Johnston. 1979. Manual of the Vascular Plants of Texas. Texas Research Foundation, Renner, Texas.

64 USGS. 1990. NAPP Series 2434, EROS Data Center, Sioux Falls, South Dakota.

6'TPWD. 1994. Unpublished maps and data files, Natural Heritage Program, Department of Resource Protection Division, Texas Parks and Wildlife Department, Austin, Texas.

66McMahan, C.A., R.G. Frye, K.L. Brown. 1982. The Vegetation Types of Texas Including Cropland. Texas Parks and Wildlife Department, Austin, Texas.

67 U.S. Fish and Wildlife Services. 1991. National Wetland Inventory Series. New Braunfels East, New Braunfels West, Schertz, Longhorn Quadrangles.

3-649 The amounts of water that could be made available on a firm basis for diversion below the City of Gonzales, Texas under various Edwards pumping scenarios by releasing stored Canyon Lake water, plus diverting under selected downstream water rights, are shown in Tables 3.41-1 and 3.41-2. The latter table also discloses the water available on a firm basis with and without application of the Trans-Texas criteria for instream flows and bay and estuary inflows to Alternative G-28. The Guadalupe River below Canyon Dam was the subject of an instream flow study during the mid 1980's, at the time a hydroelectric capability was installed, resulting in minimum flow requirements established during the FERC permitting process that were honored in developing this alternative. Because the water to be diverted at Gonzales would consist of a mix of stored water and run of river water, all of which is currently permitted, application of the Trans-Texas criteria will require additional clarification as to what water is subject to the criteria, and how (in a practical sense) they would be applied in this particular situation. At this time we can only predict that monthly median flows resulting from meeting the Trans-Texas criteria with Alternative G-28 would fall between the with and without project medians plotted in the Figures of this section. Figure 3.41-2 shows existing monthly median streamflows below Canyon Lake (period of record 1934-1989), and the changes anticipated to result from implementation of this alternative without the instream diversion limits imposed by the Trans-Texas criteria. Projected changes in streamflow patterns are very similar to those outlined in the discussion of Alternative G-27 (Section 3.40). Both positive and negative changes on the order of 10 to 20 percent are projected for late spring and summer (May-August), while substantial decreases (35-50 percent) in monthly median streamflows are expected during the remainder of the year. Figure 3.41-2 shows how streamflows would be redistributed on an annual basis: during dry years reductions in streamflow would average 5-15 percent in the lowest five deciles, while during wetter years, streamflow could increase about 6 percent. Projected changes in monthly median flows, and in annual average flows by decile, are presented for the Guadalupe River below the diversion point at Gonzales and at the Saltwater Barrier in Figures 3.41-2 and 3.41-3. At Gonzales substantial (20-25 percent) reductions in monthly median streamflows would occur during late summer and fall (July

3-650 through October), with the largest proportional impacts occurring during the driest years (Figure 3.41-2). At the Saltwater Barrier (San Antonio Bay inflows) streamflow changes as a result of implementation of this alternative would be essentially identical to those outlined in Section 3.40 (Alternative G-27). Monthly median streamflows would be reduced about 5-l 0 percent during late spring and summer (May-August), while both positive and negative changes of less than 5 percent would occur during the remaining months (Figure 3.41-3). Most of these reductions would occur during wet years, with dry year streamflows being largely unaffected (Figure 3.41-3). Alterations in streamflow patterns of the magnitudes projected to occur in the reaches below Canyon Dam may result in changes in the average abundances of some aquatic populations, increase interannual variation, and reduce the overall carrying capacity in these reaches during dry years. Existing minimum streamflow requirements established by FERC at Canyon Dam are expected to be adequate for at least minimal maintenance of the biological community in this reach, since flows during the critical summer period would be least affected. Although the peak summer recreational period would be relatively unaffected, river recreationalists would experience more, or more extended, low flow periods during the early spring and fall as a result of implementation of Alternative G-28. The potential impacts to river recreation and local economies should be examined in detail if this alternative is retained for further consideration. Below Gonzales the substantial reductions in streamflows projected to occur during the driest years, particularly during the historic summer (July-September) low flow period, may adversely affect some biological communities downstream. Reductions in San Antonio Bay inflows would approach 10 percent of the monthly medians only during May and August, and would occur primarily during wet years. Instream flow studies should be conducted in the reaches below Canyon Dam and Gonzales in order to evaluate potential impacts to the community as a whole, but more particularly to the aquatic species discussed below as being of concern to state and federal resource agencies. Because of the lack of effect on the lower flow ranges at the Saltwater Barrier, impacts to San Antonio Bay as a result of increased length or severity of drought periods do not appear to have great potential for being significant. For example, using a

3-651 1934-1989 period of record, the minimum annual flow would have decreased from 52,289 to 50,250 acre feet (4 percent) as a result of implementing Alternative G-28. In the same simulation, 25th percentile and median flows at the Saltwater Barrier are shown to decrease by only 3.4 and 1.6 percent, respectively, with only minor variation in seasonal patterns (Figure 3.41-2). Since this alternative is a diversion, not an impoundment, its operation will have minimal effects on flood flows. The Cagle's map turtle, Guadalupe bass, and the blue sucker ranges extend from the

Edwards Plateau through the Blackland Prairie to the Coastal Plains in Guadalupe River. Cagle's map turtle has been located as far south as Victoria, Texas on the Coastal Plain. Best adapted for flowing water, the Guadalupe bass is often found in flowing water near riffles feeding on aquatic insects and moving water associated fish such as the Texas shiner (Notropis amabilis) and channel catfish (leta/urns punctatus). Although the Guadalupe bass is found in reservoirs such as Canyon Lake, it may be at a competitive disadvantage with other bass species in more lentic environments. Populations of Guadalupe bass tend to decline as the river enters the Coastal Plains. In the Guadalupe River, few are found

68 downstream of Luling in Caldwell County • The blue sucker, a large river fish, is a candidate for federal protection with probable occurrence, although the presence of several dams in this reach of the Guadalupe, together with a lack of suitable substrate and flow conditions, suggests that it may no longer be present. Although the Texas Natural Heritage Program does not report any endangered or threatened species directly along the proposed pipeline corridor, some have been reported

69 70 in the vicinity · • The Texas Organization for Endangered Species (TOES) has listed the two-flower stickpea (Calliandra biflora) for special consideration and has been mapped by the Natural Heritage Program in the vicinity of a portion of the transmission corridor in Goliad County. This plant is found in shallow, well drained sandy soils of sparsely vegetated

68 Garrett, Gary P. 1991. Guidelines for the Management of Guadalupe Bass. Publication PWD-RP-N3200- 367-11/91, Texas Parks and Wildlife Department, Austin, Texas.

69TPWD. 1994. Unpublished maps and data files, Natural Heritage Program, Department of Resource Protection Division, Texas Parks and Wildlife Department, Austin, Texas.

70TOES. 1992. Endangered, Threatened, and Watch List of Natural Communities of Texas, Publication 8, Austin, Texas; TOES. 1993. Endangered, Threatened, and Watch List of Texas Plants, Third Revision, Austin, Texas.

3-652 grass and shrublands. Another Texas native plant on the TOES watch list is the Texas

71 gourd (Cucurbita texana) often found in alluvial soils on river terraces • Although we did not find this species occurrence mapped in the corridor, there is appropriate habitat for this gourd. The areas of grasslands, brush, and shrub could be habitat for several endangered or threatened species, such as the Black-capped Vireo, Golden-cheeked Warbler, Texas horned lizard, and Texas garter snake (Appendix B, Tables 6, 21 and 22, Volume 2). Surveys for the presence of important and protected species would be conducted within the proposed construction corridor. Cultural resources protection on public lands in Texas is afforded by the Antiquities Code of Texas (Title 9, Chapter 191, Texas Natural Resource Code of 1977), the National Historic Preservation Act (PL96-515), and the Archaeological and Historic Preservation Act (PL93-291). All areas to be disturbed during construction will be first surveyed by qualified professionals for the presence of significant cultural resources.

3.41.4 Water Quality and Treatability (To be completed in subsequent phases of the study.)

3.41.5 Engineering and Costing For this alternative, the combined firm water available at Gonzales would be diverted through a new intake and pump station located along the shore of the Guadalupe River and pumped in a transmission line to the proposed North Water Treatment Plant. The diversion rate from the Guadalupe River would vary considerably from month to month with highest use in the summer months needed in order to keep SAWS aquifer pumpage uniform throughout the year. The major facilities required to implement this alternative are: Reservoir Intake and Pump Station Raw Water Pipeline to Treatment Plant Raw Waterline Booster Pump Station Water Treatment Plant (Level 3, see Table 3.0-4, Volume 2) Finished Water Pump Station Distribution System Improvements

71 TOES. 1993. Endangered, Threatened, and Watch List of Texas Plants, Third Revision, Austin, Texas.

3-653 The reservoir intake and pump station is sized to deliver a maximum monthly volume of 12,400 acft ( B3 mgd) through a 90 inch diameter pipeline. The operating cost was determined for the total raw water static lift of 720 feet and an annual water delivery of 71,260 acft/yr. Financing the project over 25 years at an 8.0 percent annual interest rate results in an annual expense of $33,960,000 (Table 3.41-3). The annual cost of water purchased from GBRA is $53 per acft, for an annual payment of $1,890,000. Purchase of water using senior water rights of the Calhoun Canal Division is estimated to cost $53 per acft for firm water (same cost as stored water from Canyon Lake). For purchase of 40,000 acft/yr using senior rights, firm availability is estimated to be 37,000 acft/yr at the Saltwater Barrier (see Section 3.23, Volume 2) for an annual cost of $1,960,000. Compensation for CP&L's contract for stored water from Canyon Lake is assumed to be $53 per acft/yr and is included in the annual cost for replacement water for make-up needs at CP&L's Coleta Creek Reservoir. Operation and maintenance costs, including power and purchase of all stored, transferred and replacement water, total $24,270,000. The total annual costs, including debt repayment, interest, operation and maintenance and all water purchases, total $58,230,000, for all facilities. Included in these costs are annual costs for facilities to deliver SAWS reclaimed water from the San Antonio River to replace CP&L's cooling water needs (including compensation for CP&L's Canyon Lake stored water contract) total $1,140,000 as described in Section 3.42.5. For an annual firm yield of 71,260 acft, the resulting annual cost of water developed under this aspect of the SAWS plan is $817 per acft (Table 3.41-3).

3.41.6 Implementation Issues An institutional arrangement is needed to implement projects including financing on a regional basis. Requirements Specific to Transfer of Downstream Rights

1. CP&L and GBRA diversion permits will need to be amended to change the point of diversion. CP&L run-of-the-river permit will need to be transferred.

3-654 Table 3.41-3 Cost Estimate Summaries for Guadalupe River Diversion Near Gonzales with Transfer of Downstream Rights (G-28) (Third Quarter - 1994 Prices) Alternate G-27 Item Costs Capital Costs Intake and Pump Station $7,090,000 Transmission Pipeline and Pumping 115,090,000 Treatment Plant 53,160,000 Delivery System 1 87.350,000 Total Capital Cost $262,690,000 Engineering, Contingencies, and Legal Costs $78,050,000 Land Acquisition 420,000 Environmental Studies and Mitigation 420,000 Interest During Construction 20,780.000 Total Project Cost $362,360,000 Annual Costs Annual Debt Service $33,960,000 Annual Operation and Maintenance 10,710,000 Replacement Water Cost for Coleta Creek (Includes Makeup Water from SAWS Return Flows, including Purchase of CP&L 1,140,000 GBRA Stored Water Contract) Purchase of 35,588 acft/yr Canyon Lake Stored Water 1,890,000 Purchase of 40,000 acft/yr under Senior Water Rights from Saltwater Barrier 1,960,000 Annual Power Cost 8,570.000 Total Annual Cost $58,230,000 Available Project Yield (acft/yr) 71,260 Annual Cost of Water $817 jacft

1 As described in Section 3.0.2 delivery system improvements costs were determined from studies for delivery of Applewhite Reservoir water and may be lower for a water source on the northwest side of the city.

3-655 Requirements Specific to River Diversion and Transmission Pipeline:

1. Necessary permits: a. U.S. Army Corps of Engineers Sections 10 and 404 dredge and fill permits for stream crossings. b. GLO Sand and Gravel Removal permits. c. TPWD Sand, Gravel, and Marl permit for river crossings. d. Coastal Coordinating Council review may be required. 2. Right-of-way and easement acquisition. 3. Crossings. a. Highways and railroads b. Creeks and rivers c. Other Utilities

Requirements Specific to Treatment and Distribution

Requirements Specific to Amending the Canyon Lake Permit

1. If this alternative requires exceeding the current permitted average annual diversion from Canyon Lake of 50,000 acft, then a permit amendment will require: a. Application to the TNRCC b. Hydrologic studies substantiating requested firm yield. c. Environmental studies of in-stream flow and bay/estuary effects. d. Subordination of hydropower rights. e. Management of Edwards Aquifer by a regional agency to achieve the modeled aquifer pumpage/springflow scenario.

3-656 3.42 Use of SAWS Reclaimed Water to Replace Potential Water Transfers (L-20) 3.42.1 Description of Alternative In previous sections, water rights held by Central Power & Light (CP&L) for their Coleto Creek generating station and rights held by GBRA at their Calhoun Canal Division (GBRA CCD) have been studied for potential amendment to allow diversion at Lake Dunlap or near Gonzales. See Section 3.40 Diversion at Lake Dunlap with Transfer of Downstream Rights (G-27) and Section 3.41 Diversion Near Gonzales with Transfer of Downstream Rights (G-28). This alternative considers diverting a portion of SAWS return flow from the San Antonio River near Goliad and transferring it to Coleto Creek Reservoir, thereby mitigating, to the extent possible, the effects of transferring CP&L rights to upstream locations under Alternatives G-27 and G-28. Additionally, mitigation for using GBRA CCD water at locations other than the Saltwater Barrier could be accomplished, in part, with return flows remaining at the Saltwater Barrier after all upstream uses and channel losses are considered including SAWS/SARA tunnel reuse of 18,000 acft/yr, makeup water demands for Braunig and Calaveras Lakes and Coleto Creek Reservoir, and use by existing water rights along the main stem of the San Antonio River. The major facilities needed for this alternative include a small diversion dam on the San Antonio River, water intake and pump station, a 6.5 mile transmission pipeline to Coleto Creek Reservoir, and a discharge structure near the reservoir. A possible location of the diversion near Goliad and pipeline route to Coleto Creek are shown in Figure 3.42-1.

3.42.2 Available Yield As indicated in Section 3.2 (Volume 2), a substantial quantity of reclaimed water or return flow is available from SAWS wastewater treatment plants on an annual basis. The Guadalupe - San Antonio River Basin Model72 (GSA Model) was utilized to quantify excess SAWS return flows delivered to Goliad for potential mitigation of water rights transfers in the lower Guadalupe River Basin. Excess return flows are those remaining after needs at Braunig and Calaveras Lakes, the Central East Infrastructure Project (i.e. ''Tunnel

72 HDR Engineering, Inc., ''Guadalupe- San Antonio River Basin Recharge Enhancement Study," Volumes I, II, and III, Edwards Underground Water District, September 1993.

3-657 Central Texas Plateau Texas Black/and Prairies East Central Texas Plains • Texas Black/and Prairies East Central N Texas Plains' 1 /~ /

EXISnNG DIVERSION AND PIPELINE

H Western Gulf Coastal Plains

''"'""''"·- POSSIBLE DIVERSION LOCATION AND PIPELINE ROUTE ... :

Legend TRANS TEXAS WATER PROGRAM I '- - Basin Divide WEST CENTRAL STUDY AREA Possible Pipeline Route ~ Eooregion TRANSFER OF SAWS RECLAIMED WATER Hl{ TO COLETO CREEK RESERVOIR 0 10 20 Miles ALTERNATIVE L-20 II I I. I I Scale HDR Engineering, Inc. FIGURE 3.42-1 Reuse" project), and intervening mainstem water rights on the San Antonio River have been satisfied and channel losses are considered. Braunig Lake's makeup needs were first met from its run-of-the-river water right (12,000 acft/yr) and additional makeup needs were met from SAWS return flows. Currently, make-up water for Coleta Creek Reservoir is provided from run-of-the river rights and stored water released from Canyon Lake (by contract with GBRA). CP&L holds a diversion permit for 20,000 acft/yr of run-of-the-river water from the Guadalupe River. Under this permit water is diverted at a maximum diversion rate of 35.65 cfs (70.6 acft/day) at a pump station upstream of Victoria. GBRA is under contract with CP&L to release water from Canyon Lake for pump-over to Coleta Creek Reservoir through the same pump station on the Guadalupe River. The contract with GBRA provides for the delivery of a maximum of 18,900 acft in any one-year period and 30,000 acft in any five-year period. An analysis was performed to compare availability of SAWS return flows (delivered to Goliad) to the availability of Guadalupe River water under the existing rights and contract. Availability of Guadalupe River water under the existing rights and contract was estimated for an Edwards aquifer pumpage scenario of 400,000 acft/yr, hydropower requirement of 600 cfs at Lake Dunlap, and return flows at 1988 levels. Table 3.42-1 compares average annual makeup diversion, drought average makeup diversion, and the percent of time that the CP&L makeup water need would not have been fully satisfied from each of the alternative makeup water sources. At times when makeup water needs are not fully met, the steam-electric plant remains in operation, but must operate with the cooling reservoir at a lower surface elevation than desired, possibly resulting in higher reservoir temperatures and lower plant efficiencies. Table 3.42-1 shows that an average of 8,400 acft/yr of makeup water could be diverted from SAWS return flows at Goliad on an average annual basis. This is about 89 percent of the makeup available and diverted under existing conditions. During the drought of record, an average of 12,370 acft/yr of makeup water could be diverted from SAWS return flows at Goliad, which is about 80 percent of the makeup available and diverted under existing conditions. Makeup water available for Coleta Creek Reservoir at Victoria under existing conditions would result in the makeup needs not being fully met 14.6 percent

3-659 Table 3.42-1 Makeup Water Availability for Coleto Creek Reservoir Makeu_p_ Water Source Guadalupe River SAWS Return Flows Run-of-the-River Rights and Delivered to Goliad Canyon Lake Contract 1 Via the San Antonio River 2 Average Annual Makeup 9,490 8,400 Diversion (acft/yr) 3 Drought Average Mrfeup 15,500 12,370 Diversion (acft/vr 4

Percent of Time Make~ Needs 14.6% 23.5% Not Fully Met

1 Represents existing conditions with Coleta Creek Reservoir makeup diversions from Guadalupe River under run-of-the-river water right (20.000 acftlyr) and Canyon Lake contract, 400.000 acftlyr aquifer pumpage scenario. hydropower requirement of 600 cfs at Lake Dunlap, and 1988 return flows. 'Represents Coleto Creek Reservoir makeup diversions from SAWS return flows (19881evels) delivered to Goliad after needs of SAWS/SARA Tunnel Reuse Project. Braunig and Calaveras Lakes, and existing water rights owners along the main stem of the San Antonio River are met. 3 Represents average annual makeup diversions for the 1934-89 period subject to water availability and a maximum diversion rate of 35.65 cfs. 'Represents drought average makeup diversions for the 116 month period beginning in July. 1947 and ending in February. 1957 subject to water availability and a maximum diversion rate of 35.65 cfs. ' Percent of time that the makeup need was not fully met due to the limits of water availabilitY or maximum diversion rate. of the time or 98 months out of the 672 month period analyzed (1934-89). In comparison, makeup water available from SAWS return flows at Goliad would result in the makeup needs not being fully met 23.5 percent of the time or 158 months out of the 672 month period analyzed. The lack of makeup water available from SAWS return flows at Goliad in certain months is largely due to the demands on SAWS return flows for upstream uses including tunnel reuse and Braunig and Calaveras Lakes as well as losses in delivery of reclaimed water down the San Antonio River. Comparisons were also made of minimum annual Cole to Creek Reservoir pool levels with makeup water from the Guadalupe River at Victoria under existing conditions and with makeup water available from SAWS return flows at Goliad. The results are presented in Table 3.42-2 and Figure 3.42-2. For makeup water supply from SAWS return flows, Table 3.42-2 shows that Coleto Creek Reservoir would operate at or below a one-foot drawdown level about 9.8 percent of time compared to only 0.4 percent of the time for existing conditions. Figure 3.42-2 shows a comparison of minimum annual Coleto Creek Reservoir pool levels for the 1934-89 period for both existing conditions (makeup from Guadalupe River) and with the makeup supply from SAWS return flows from the San Antonio River. The minimum reservoir pool level with the makeup supply from SAWS return flows at

3-660 100.0- 100.0 ::::1 II) :E 99.0 99.0 1-' L&. 98.0 ~ 111111111111:,., Ill• 98 0 -...J II n n 0 w ~::~~~~~~~~~~~~~~~~~~----~ll~~li--~~~nf~ij'L~/1~~~1·l'I.Jni-J'.(]'.~"lfi:~,.~J'1'·~~~~~~~~~~·~~rn "" 97.. >w 97.0 --= f----- f-llif-ll1f- ...J ...J 0 96.0 __:: f-ll--if- t- 96.0 0 11. 0:: 95.0 --= [ 95.0 0 > 94.0 --= f- 94.0 0::w II)w 93.0 __:: 93.0 0:: :E ::1 92.0 __:: f- 92.0 ~ z 91.0 __:: 91.0 :E - 9o.o 'gl~l~l~l~l~lgl~l~l~l~l~l~l~l~l~l~l~l~l~l~l~l~l~l~lml2l~l~l~l~l~l~l~l~lml~l~l~l~l~l~l~l~l~l~l~l~l~l~l~l~l~l~l~l~ 90.0 m~~~m~~mmmmmmmmmmmmmmm~mmc~mm~~~mm~~mmmmmmmmmmmmmmmmmmmm ~~~------YEAR

0 MAKEUP FROM GUADALUPE RIVER UNDER EXISTING RUN OF RIVER RIGHT AND CANYON CONTRACT • MAKEUP FROM SAWS RETURN FLOWS DELIVERED TO GOLIAD

Assumptions: TRANS TEXAS WATER PROGRAM I 1. Return flows at 1988 amounts; 400,000 ac-ftlyr aqu~er pumpage scenario; hydro requirement of 600 cfs at Lake Dunlap for makeup from WEST CENTRAL STUDY AREA Guadalupe River. 2. Return flows at 1988 amounts; 368,000 ac·Wyr aquifer pumpage scenario; and hydro requirement of 0 cfs at Lake Dunlap for makeup COMPARISONS OF COLETO CREEK from SAWS return flows. 3. Return flows for Coleta Creek Reservoir make-up water after needs of RESERVOIR MINIMUM POOL LEVELS Braunig/Calaveras reservoirs, Tunnel Reuse and intervening water rights and losses. Hl~ ALTERNATIVE L-20 4. Maximum diversion rate 35.65 cfs for both sources. HDR Engineering, Inc. FIGURE 3.42-2 Table 3.42-2 Comparison of Coleto Creek Reservoir Pool Levels Makeup Water from Makeup Water from SAWS Guadalupe River Rights and Return Flows Delivered to Reservoir Canyon Lake Contract 1 Goliad 2 Area and Caoacitv Reservoir Number of Percent of Number of Percent of Pool Months at or Time at or Months at or Time at or Surface Storage Level Below Level 3 Below. Level Below Level 3 Below. Level Area C~pa~~ty (ft-MSL) (acreS) acft 98.0 672 100.0% 672 100.0% 3,100 35,084 97.0 3 0.4% 66 9.8% 2.920 32 074 96.0 I 0.2% 26 3.9% 2.740 29,244 95.0 0 0.0% II 1.6% 2.570 26,589 94.0 0 0.0% 4 0.6% 2.400 24,104 1 Represents the existing conditions of Coleta Creek Reservoir makeup diversions from Victoria under the exisung run-of-the-river water right (20.000 acft/yr) and Canyon Lake contract. Aquifer demand scenario at 400,000 acft/yr and hydropower subordinated to 600 cfs at Lake Dunlap. The minimum reservoir pool level was 95.8 ft-msl. 2 Represents the conditions of Coleta Creek Reservoir make~diversions from SAWS return tlows delivered to Goliad after tunnel reuse and Braunig and Calaveras s makeup needs have been met from SAWS return tlows. Aquifer demand scenario at 368,000 acft/yr and hydropower subordinated to 0 cfs at Lake Dunlap. The minimum reservoir pool level was 91.8 ft-msl with the diversion rate limited to 35.65 cfs. With a diversion rate of 56 cfs, the minimum pool level would have been about 93.8 ft-msl. 3 The number of months that the reservoir pool was at or below the indicated level. The 1934-89 period (672 months) was used for the simulations. 4 The percent of time during the 1934-89 period that the reservoir was at or below the indicated reservoir pool level.

Goliad was found to be 91.8 feet-msl in 1956 as compared to 95.8 feet-msl for existing conditions. If the maximum diversion rate for makeup water supply from SAWS return flows at Goliad were increased from 35.65 cfs to 56 cfs, the minimum reservoir pool level would be approximately 93.8 feet-msl.

The availability of SAWS return flows at the Saltwater Barrier was determined in order to evaluate the potential for mitigation of GBRA water rights transferred from the Saltwater Barrier to upstream locations. Figure 3.42-3 shows the annual total of SAWS return flow available at the Saltwater Barrier after all upstream uses are satisfied to the extent possible. Upstream uses include SAWS/SARA tunnel reuse, makeup demands for Braunig Lake and Calaveras Lake, makeup demands for Coleto Creek Reservoir, and use by existing water rights owners on the main stem of the San Antonio River. The availability of SAWS return flows at the Saltwater Barrier also accounts for channel losses from San Antonio to the Saltwater Barrier. The minimum simulated annual volume of SAWS return flow available at the Saltwater Barrier would have been 2, 700 acft in 1956. This is about 2.0 percent of the total annual SAWS return

3-662 60,000 - 55,000 - 50,000

45,000 -f--- ~ - ct w 40,000 -

II..~ 35,000 - 0' ct 30,000 = -~ 0 = ..J = II.. 25,000 z = a::: = ::l 20,000 1-w = a::: 15,000 = = 10,000 = = 5,000 = = = II 0 ~~~~~~~~~~~~21~1~1~131~1~r~r~r~r~r~r~r~r~r~r~r~rmrmr~r~r~r~r~r~r~,~,0'~'~'~'~'~'~··-..... ,..... t1\- ~at tr1 - ~ !.0 t-:1~1~ ~~;;; ~ ~ ~ ~ !R ~!i ~ mmmmmm~~mammmmmmmmmmmmmmmm~mmmmmmmmmmmmmmmmmmmmmmmmmmmmm·-··- ·- ·- ______~~~~~~~~------YEAR

TRANS TEXAS WATER PROGRAM I Assumptions: WEST CENTRAL STUDY AREA 1. Return flows at 1988 amounts; 368,000 ac-tvyr aquifer pumpage scenario; hydro requirement of 0 cfs at Lake Dunlap. 2. Return flow availability after needs of Braunig/Calaveras reservoirs, Tunnel Reuse, Coleta Creek Reservoir, and intervening water rights and losses. AVAILABILITY OF SAWS RETURN FLOWS AT SALTWATER BARRIER lil~ ALTERNATIVE L-20 HDR Engineering, Inc. FIGURE 3.42-3 flow of 136, 100 acft. For the 1956 condition, upstream uses of SAWS return flow include SAWS/SARA tunnel reuse in the amount of 18,000 acft (13.2 percent), Braunig Lake makeup demand of 17,100 acft (12.6 percent), Calaveras Lake makeup demand of 56,700 acft (38.7 percent), Coleta Creek makeup demand of 14,200 acft (10.4 percent), and existing water right demands of 5,300 acft (3.9 percent) on the mainstem of the San Antonio River. Channel losses between San Antonio and the Saltwater Barrier would have depleted SAWS return flows by 26,100 acft (19.2 percent). Comparisons of monthly median streamflows and annual streamflows averaged by decile are presented in Figure 3.42-4 for the San Antonio River at Goliad for conditions both with and without the diversion of SAWS return flows for Coleto Creek Reservoir makeup. The streamflow statistics presented are for an aquifer demand of 368,000 acft/yr with the project and 400,000 acft/yr without the project while return flows are set at 1988 levels. The results show a small reduction in the median monthly streamflow in almost all months with the largest reductions of 9 percent, 13 percent, and 11 percent occurring in July, August, and September, respectively. The reduction in the median monthly streamflow was found to be less than 3 percent in all other months. Figure 3.42-4 also shows a reduction in the average annual streamflow in each of the deciles with the project. The largest decrease in average annual streamflow was found to be about 13 percent in the lowest streamflow decile. The impact is less than 1 percent in those years of highest streamflow.

3.42.3 Environmental Issues The area potentially affected by this alternative includes the San Antonio River south of Goliad, Coleto Creek Reservoir in the Guadalupe River basin and a pipeline corridor between the diversion point and reservoir. This area encompasses a landscape typical of the East Central ?Texas Plains (Figure 3.0-1, Volume 2). Both the San Antonio River and the Guadalupe River

73 in the project area flow through nearly level bottomland hardwood corridor • Coleto Creek Reservoir was completed in 1980 to provide recirculating cooling water for a CP&L electric generating station. Normal pool elevation is 98 feet-msl, spillway elevation is about 107 feet-

73 USFWS. 1991. National Wetland Inventory Map Series. Fannin and Hensley Lake, Texas Quadrangles. USGS.

3-664 SAN ANTONIO RIVER AT GOUAD SAN ANTONIO RIVER AT GOUAD

1,200,000 -- 30,000

1,100,000 f' 1,000.000 ··- !z 20,000 - ~ 1100,000 if ~ 1100,000 & ,.,000 & ~ 700,000 000,000 c--- ~ UI,OOO ~ j ~ \ ~ 000,000 ~ w ~ 10,000 -800.000 F ~ I ~ 0 •ooo " -100,000 ~.,_..,. !!11~ .1.f!ia0Jj, &1~'K. tf-71)% I 71~ I 11410% I 81-100% ... FEB I MAR I APR I MAY ...... AUQ I SEP I OCT I NOV I DEC 00 00 MONTHS STREAMFLOW DECILES

TRANS TEXAS WATER PROGRAM I LEGEND: WEST CENTRAL STUDY AREA • WITH PROJECT CHANGES IN STREAMFLOW ·SAN ANTONIO D WITHOUT PROJECT RIVER AT GOLIAD WITH SAWS RETURN FLOWS --TRANS-TEXAS ENVIRONMENTAL CRITERIA lil~ ALTERNATIVE L-20 HDR Engineering, Inc. FIGURE 3.42-4 74 msl and top of dam is 120 feet-msl • The littoral of the relatively shallow reservoir ts typically tlat and seasonally tlooded. Lower perennial wetlands with emergent vegetation are present in the area of the proposed discharge point, while higher elevations around the reservoir

75 76 consist of upland forested knolls of pecan and elms • • The estimated 23.6 acre construction corridor for the water transmission line assessed as Alternative L-20 traverses areas comprised primarily of mesquite invaded coastal post oak woods, and a forest and grassland mosaic developed on the sandy soils of the Post Oak Savannah

77 78 (Volume 2; Figure 3.0-2, Figure 3.42-1) · • The dominant species, post oak, occurs in open stands with a grass ground cover. The vegetation type is either considered to be part of the

79 80 1 2 83 84 85 Eastern Deciduous Forest association or as part of the Prairie association • ·H ,H • • • • The latter association is based upon the occurrence of a climax tall grass understory composed of prairie dominants, little bluestem, Indiangrass, and big bluestem. Recent agricultural

74 HDR Engineering, Inc. 1994. Pers. Comm. Coleta Creek design drawings.

75USFWS. 1991. National Wetland Inventory Map Series. Fannin and Hensley Lake, Texas Quadrangles. USGS.

76USGS. 1989. NAPP Photograph 1540-161 dated 2-23-89. EROS Data Center, Sioux Falls, South Dakota.

77 McMahan, CA., R.G. Frye, K.L. Brown. 1982. The Vegetation Types of Texas Including Cropland. Texas Parks and Wildlife Department, Austin, Texas.

78Gould, F.W. 1975. Texas plants--a Checklist and ecological summary. Texas A&M University. Texas Agricultural Experiment Station. MP-585/Rev. College Station, Texas.

19Correll, D.S., and M.C. Johnston. 1979. Manual of the Vascular Plants of Texas. Texas Research Foundation, Renner, Texas.

80Tharp, B.C. 1939. The vegetation of Texas. Texas Acad. Sci, Anson Jones Press, Houston, Texas.

"Braun, E.L., 1950. Deciduous forest of eastern North America. Hafner Pub!. Co., Inc. New York.

"Mahler, W.F. 1980. The mosses of Texas. Southern Methodist University Herbarium, Dallas, Texas.

84Weaver, J.E. and F.E. Clements. 1938. Plant Ecology. 2nd Ed. McGraw-Hill Book Co., New York.

85Daubenmire, Rexford. 1978. Plant geography with special reference to North America. Academic Press, New York.

3-666 practices, such as overgrazing, abandonment from cultivation, and fire control, has contributed to many acres being converted into dense woodland stands of post oak and winged elm. The only stream to be crossed by the proposed transmission line corridor is Manahuilla

6 Creek, a seasonally intermittent tributary to the San Antonio River" • In this reach of the San Antonio River (and Manahuilla Creek) wetlands are generally limited to the streambed itself, as

87 the relatively steep, forested banks support mesic, upland woods dominated by pecan and elm • The post oaks-mesquite savannah occupies about 90 percent of the corridor. Upland hardwood forests, including those along the stream banks, total about 8 percent of the corridor. Developed areas along the transmission line corridor total less than 1 percent and wetlands occupy the remaining 1 percent. The important species listed in Appendix B, Tables 20 and 44 (Volume 2) for Goliad and

88 Victoria counties apply to the Alternative L-20 area • Three important birds may be found using habitat found in the study area. They are the American Bald Eagle, the White-tailed Hawk, and White-faced Ibis. The American Bald Eagle is known to nest along densely forested corridors of the San Antonio and Guadalupe River bottoms. The rare White-tailed Hawk is found in grasslands and coastal prairie of the Texas Gulf Coast. The White-faced Ibis has been reported as a summer resident in freshwater marshes and hardwood bottomlands south of the project area. Texas scarlet snake, listed as threatened by Texas Parks and Wildlife Department, and the Texas horned lizard, which is also a candidate for federal protection, are the most likely important species to found in upland habitats of the study area. The semi-fossorial Texas scarlet snake is found on sandy soils of East Texas and the central and south Gulf Coast. The Texas horned lizard is a denizen of open, well-drained habitats with sparse cover. Ants, spiders, and isopods are included in their diets. The decline of Texas horned lizard populations is associated

"'USFWS. 1991. National Wetland Inventory Map Series. Fannin and Hensley Lake, Texas Quadrangles. USGS.

87 McMahan, C.A., R.G. Frye, K.L. Brown. 1982. The Vegetation Types of Texas Including Cropland. Texas Parks and Wildlife Department, Austin, Texas.

88Texas Parks and Wildlife Department, Unpublished 1994. September, 1994, Data and map files of the Natural Heritage Program, Resource Protection Division, Austin, Texas.

3-667 9 with the invasion of fireants, agricultural practices and urbanization' • This statewide species preferred habitat is open, flat terrain with bare ground. Important aquatic species known to the San Antonio River and Guadalupe River include the Guadalupe bass and Cagle's map turtle. Both species are reported in the Guadalupe River

90 91 92 basin around Victoria · · • Populations of Guadalupe bass tend to decline as the river enters the Coastal Plains. The proposed diversion dam on the San Antonio River, surface intake and pump station would likely effect an estimated two acres of riverine wetlands. The transmission line from the San Antonio River diversion to Coleto Creek is estimated to be about 6.5 miles long, and to require a 30 foot construction corridor, within which an estimated 21 acres of post oak and grassland mosaic vegetation and 0.25 acres of intermittent streambed may be disturbed. The proposed discharge structure at Coleto Creek would disturb about a quarter acre of palustrine wetlands with emergent vegetation. With all major facilities included, the total area potentially disturbed during construction will be about 26 acres. A ten foot right of way (ROW), totaling 7.9 acres free of woody vegetation, would be maintained for the life of the proposed transmission line. The small diversion dam and intake at San Antonio River, about half an acre, would permanently affect water diversion and riverine wetlands for the life of the project. The associated pump station may affect an estimated quarter acre of post oak uplands for the life of the project. The discharge structure would permanently affect an estimated quarter acre of littoral zone in vegetated wetlands of Coleto Creek Reservoir. The location of the proposed alternative facilities and transmission line alignment are now only generally specified (Figure 3.42-1). The primary long term effect on Coleto Creek Reservoir will be increased fluctuations in water surface elevation. Alternative L-20 would replace the Guadalupe River water with SAWS reclaimed effluent. The reservoir would operate at or below a one foot drawdown level about 9.8 percent of the time, and would experience drawdowns greater than 4 feet 0.6 percent

9 ' Price, A., W. Donaldson, and J. Morse. 1993. Final Report As Required by the Endangered Species Act, Section 6, Texas Project No. E-1-4. Texas Parks and Wildlife Department, Austin, Texas.

90Gary P. Garrett. 1991. Guidelines for the Management of Guadalupe Bass. TPWD Austin, Texas.

"Haynes, David and Ronald R. McKown. 1974. A new species of map turtle (Genus Graptemys) from the Guadalupe River System in Texas. Tulane Studies in Zoology and Botany, Vol. 18, Num. 4. pp. 143-152.

92 Killebrew, Flavius C. and Dan A. Porter. 1991. Testudines, Graptemys caglei. Herp Review: 22(1), p. 24.

3-668 of the time (Table 3.42-2, Figure 3.42-2). Although substantially less stable than historical water surface elevations, the changes in elevation that would accompany implementation of this alternative do not appear to exceed a rate of about 2 feet/year except during extreme drought periods. This would not substantially affect fish reproduction in shallow water. Potential effects on reservoir water quality and recreational use of the reservoir are not addressed in this phase of the study, but should be addressed if this alternative is considered further. While changes in monthly median stream flows in the San Antonio River below the Goliad diversion during most months would be quite small, the historically lowest flow months (July through September) would exhibit median flow reductions of 8-13 percent93 (Figure 3.42-4). Figure 3.42-4 shows flow reductions distributed relatively evenly over all but the highest annual flow deciles, with the largest proportional reduction (13.2 percent) in the lowest flow decile (Figure 3.42-4). Reductions in minimum flows would average about 13 percent, and range as high as 39 percent during the summer months. On the other hand, flow reductions in both monthly 25th percentile and median flows would be much less, averaging 7.5 and 0.9

94 percent , respectively, on an annual basis. Changes of this magnitude in streamflow regime may have some detectable effects on !otic communities, so an evaluation of the potential for these impacts to occur, and their predicted nature, and extent, should be conducted if this alternative is considered further. Protected species that appear most likely to be encountered during construction of this alternative include the American Bald Eagle, White-faced Ibis, Texas scarlet snake and the Texas horned lizard in forested and upland areas. Potential conflicts with the birds and reptiles should be easily avoidable with appropriate habitat and important species surveys. Cagle's map turtle and the Guadalupe bass may be present in the project area. Potential conflicts should be avoidable by employing appropriate habitat and important species surveys (including instream flow evaluations) and appropriate construction techniques. A cultural resources survey of all public property, including easements held by public entities, to be disturbed during construction is required by the Antiquities Code of Texas (Title 9, Chapter 191, Texas Natural Resources Code of 1977). Any sites located would be tested for

93 HDR Engineering, Inc., 1994. Unpublished hydrologic model results. Austin, Texas.

94 Ibid.

3-669 significance and eligibility for the National Register. Disturbance of significant sites should be avoided to the extent possible.

3.42.4 Water Quality and Treatability [To be completed in subsequent phases of the study.]

3.42.5 Engineering and Costing For this alternative, SAWS return flows would be diverted at a location on the San Antonio River downstream of Goliad and pumped to Coleto Creek Reservoir to provide makeup water for steam-electric cooling needs to replace the run-of-the-river and stored water contracts currently in place for Guadalupe River water. Facilities needed to implement this alternative include: Small Diversion Structure in the San Antonio River Surface Water Intake Pump Station Transmission Pipeline Discharge Structure in the Coleto Creek Reservoir

Cost of Purchased Water Under Water Trades The San Antonio Water System (SAWS) would supply reclaimed water to CP&L to replace to the extent possible the current make-up water sources for Coleto Creek Reservoir. Replacement of CP&L's run-of-the-river diversion right would be compensated for by SAWS making reclaimed water available. Additionally, SAWS would compensate CP&L for the cost of the facilities to provide that water. Because the diversion right would be replaced with other water, no direct payment is anticipated to CP&L for their run-of-the-river water right and SAWS would not be paid by CP&L for providing reclaimed water. Currently, CP&L holds a contract with GBRA to purchase up to 30,000 acft in any five year period of stored water from Canyon Lake which is equivalent to an annual volume of 6,000 acft. Two alternative approaches could be considered to modify the stored water purchase contract. The contract between CP&L and GBRA could be maintained in force, in which case SAWS would reimburse CP&L for the payments to GBRA and SAWS would then divert the Canyon Lake stored water at Lake Dunlap or Gonzales. Alternatively, the CP&L-GBRA contract could be cancelled and replaced by a contract between SAWS and GBRA, in which case

3-670 SAWS would pay GBRA directly for stored water. Under either payment option, the cost to SAWS has been estimated at $320,000 per year which is based on the current cost of Canyon Lake water and this cost is included in the following cost estimate.

Cost of Facilities The pump station capacity for the new intake located on the San Antonio River is set at 35.65 cfs, matching the capacity of the existing diversion facility on the Guadalupe River supplying makeup water to Coleto Creek Reservoir. The new pipeline to Coleto Creek Reservoir would be 36 inches in diameter and 6.5 miles in length. The operating cost was determined for a static lift of 70 feet and an annual water delivery of 8,400 acft/yr. Financing the project over 25 years at an 8 percent annual interest rate results in an annual cost of $600,000 (Table 3.42-3). Average annual operation and maintenance costs, including power, total $220,000. Compensation for water purchased by SAWS under the CP&LJGBRA Canyon contract is estimated to be $320,000 acft/yr. Total annual costs, including debt repayment, interest, water contract purchase, and operation and maintenance, total $1,140,000. For an annual firm yield of 8,400 acft, the resulting annual cost of makeup water is $136 per acft (Table 3.42-3). The annual cost of this component of the SAWS plan is included as part of the cost of Alternatives G-27 and G-28 (diversions at Lake Dunlap and Gonzales) which include diversions of the Canyon Lake and Guadalupe River water made available under this replacement option.

3.42.6 Implementation Issues Requirements Specific to Use of Coleto Creek Reservoir:

1. Studies need to be performed to determine if the reduced make-up water supply available from reclaimed water presents a problem for the operation and efficiency of CP&L's generating station and for the operation of GBRA's recreation operations at the reservoir. If additional make-up water supplies are needed, other water is potentially available from: increased SAWS return flows; maintaining a portion of CP&L's contract with GBRA for purchase of stored water; temporary releases of reclaimed water stored in Braunig and/or Calaveras; temporary make-up from groundwater supplies; construction of a larger capacity pump station and pipeline; or some combination of these options. 2. If reservoir levels are decreased, pumping costs at the plant as well as reservoir water temperatures will increase.

3-671 Table 3.42-3 Cost Estimate Summaries for Transfer of SAWS Reclaimed Water to Coleto Creek Reservoir (L-20) (Third Quarter - 1994 Prices) Alternate L-25 Item Costs Capital Costs Channel Dam, Intake and Pump Station $1,720,000 Transmission Pipeline and Discharge Structure 2.890.000 Total Capital Cost $4,610,000 Engineering, Contingencies, and Legal Costs 1,440,000 Land Acquisition 60,000 Environmental Studies and Mitigation 60,000 Interest During Construction 250.000 Total Project Cost $6,420,000 Annual Costs Annual Debt Service $600,000 Annual Operation and Maintenance 80,000 Annual Power Cost 140,000 Compensation for CP&L-GBRA Canyon Lake Contract 320.000 Total Annual Cost $1,140,000 Annual Water Delivery (acft/yr) 8,400 Annual Cost of Water $136 per acft

3. Contract between CP&L and GBRA for delivery of Canyon Lake water would be either: a. maintained in force and SAWS would reimburse CP&L for use of the stored water; or, b. cancelled and SAWS would negotiate a purchase contract for stored water with GBRA. 4. CP&L's run-of-the-river diversion permit on the Guadalupe River would be either abandoned or transferred allowing SAWS to pursue permits for diversion of the water at either Lake Dunlap or Gonzales. 5. Studies should be performed of water quality issues (i.e. nutrient and dissolved solids loadings and possibly others) for use of San Antonio return flows as makeup up water at Coleta Creek Reservoir.

3-672 Requirements Specific to River Diversion and Transmission Pipeline:

1. Necessary permits: a. U.S. Army Corps of Engineers Sections 10 and 404 dredge and fill permits for stream crossings. b. GLO Sand and Gravel Removal permits. c. TPWD Sand, Gravel, and Marl permit for river crossings. d. Coastal Coordinating Council review may be required. 2. Right-of-way and easement acquisition. 3. Crossings: a. Highways and railroads b. Creeks and rivers c. Other utilities

Requirements Specific to Obtaining Permit to Divert Return Flows:

1. Necessary permits: a. Bed-and-Banks transfer permit from TNRCC

3-673 THIS PAGE INTENTIONALLY LEFT BLANK.

3-674 APPENDIX E

SUMMARY TABLES OF POTENTIAL WATER SUPPLY ALTERNATIVES . TABLE ES-11 SUMMARY OF POTENTIAL WATER SUPPLY ALTERNATIVES FOR THE TRANS-TEXAS WATER PROGRAM WEST CENTRAL STUDY AREA- VOLUME 3 Unit Cost of Additional Water (1994 Dollars) ($/Acft/Yr) Imported Recharge Firm Water Treatment & 1 Supply > Natural Without With Municipal Alternative (Acft/Yr) Recharge Treatment Treatment Distribution Other Environmental Issues/Special Concerns GBRA REGIONAL WATER SUPPLY PLANS

G-23 Canyon Lake Area Water Supply (a) Projected year 2050 water demand. A Areas Adjacent to Canyon Lake 5,441 (a) $995 (b)(2) (b) Cost for delivery of wholesale water supply for year 2020 demands. 2 B Smithson Valley, Bulverde, and Oak 2,095 (a) $1,467 (bY ) Village North Areas G-24 Wimberley and Woodcreek Water 2,424 (a) $950 (b)'"' (a) Projected year 2050 water demand. Supply from Canyon Lake (b) Cost of wholesale delivery to Wimberley/W oodcreek combined with Canyon Lake Regional system (Alt. G-23A) for year 2020 demands. G-25 Northeast Hays and Northwest 4,310 (a) $1,204 (b)<"' (a) Projected year 2050 water shortage. Caldwell Counties Water Supply (b) Cost for delivery of wholesale water I from Near Lake Dunlap supply for year 2020 demands. G-26 Mid-Cities (IH-35 and Highway 78) 24,294 (a) $477 (c)<"' (a) Comal/Guadalupe Co. area projected Water Supply from Near Lake 16,757 (b) year 2050 water shortage. Dunlap 41,051 (b) Northeast Bexar Co. area projected year 2050 water shortage. (c) Cost for delivery of wholesale water supply for year 2020 demands. -

(1) WATER SUPPLY VALUES FOR EACH ALTERNATIVE ARE ON A STAND-ALONE BASIS AND CANNOT BE ADDED TO OTHER ALTERNATIVES IN THEIR PRESENT FORM. (2) Costs for supply systems in the GBRA planning areas, which have capacity to meet peak demands~ are typically higher when compared to alternatives in Volume 2, which are mostly larger projects with uniform annual delivery rates.

Note: Alternatives are classified into four categories: Natural Recharge is recharge to the aquifer with water originating from the Edwards Plateau catchment, recharge zone, or from springs originating from the Edwards. Natural recharge to the aquifer can be accomplished through an injection well or recharge zone. Imported Recharge is recharge to the aquifer with all or a portion of the water originating from sources other than those listed under Natural Recharge, regardless of the delivery system into the aquifer. Treatment and Distribution considers alternatives which would include conventional water treatment, or just disinfection in the case of Carrizo water. Distribution costs will be based on costs as estimated in previous studies for delivery to the SAWS system. Other use includes demand reduction by conseJVation, reclaimed water reuse, transfer of water through purchase or lease, and treatment of brackish water by demineralization.

W:\07755001\SUMMARY.TBL Page 1 of 2 TABLE ES-11 (continued) SUMMARY OF POTENTIAL WATER SUPPLY ALTERNATIVES FOR THE TRANS-TEXAS WATER PROGRAM WEST CENTRAL STUDY AREA- VOLUME 3 Unit Cost of Additional Water (1994 Dollars) ($/Acft/Yr) Imported Recharge Firm Water Treatment & Supply0 l Natural Without With Municipal Alternative (Acft/Yr) Recharge Treatment Treatment Distribution Other Environmental Issues/Special Concerns G-27 Guadalupe River Diversion Near 78,600 (a) $581 (a) (a) Includes cost of SAWS reclaimed Lake Dunlap with Transfer of 49,785 (b) $739 (h) water for Coleto Creek makeup. Instream Downstream Rights environmental criteria not applied. (b) Includes cost of SAWS reclaimed water for Coleto Creek makeup. lnstream environmental criteria applied. , G-28 Guadalupe River Diversion Near 71,260(a) $817 (a) Includes cost of SAWS reclaimed Gonzales with Transfer of water for Coleto Creek makeup. lnstream Downstream Rights environmental criteria not applied. L-20 Use of SAWS Reclaimed Water to 8,400 Costs are included in Alternatives G-27 and G-28 (Guadalupe Replace Potential Water Transfer River Diversions with Water Rights Transfer) ------

(I) WATER SUPPLY VALUES FOR EACH ALTERNATIVE ARE ON A STAND-ALONE BASIS AND CANNOT BE ADDED TO OTHER ALTERNATIVES IN THEIR PRESENI" FORM. (2) Costs for supply systems in the GBRA planning areas, which have capacity to meet peak demands, are typically higher when compared to alternatives in Volume 2, which are mostly larger projects with uniform annual delivery rates.

Note: Alternatives are classified into four categories: Natural Recharge is recharge to the aquifer with water originating from the Edwards Plateau catchment, recharge zone, or from springs originating from the Edwards. Natural recharge to the aquifer can be accomplished through an injection well or recharge zone. Imported Recharge is recharge to the aquifer with all or a portion of the water originating from sources other than those listed under Natural Recharge, regardless of the delivery system into the aquifer. Treatment and Distribution considers alternatives which would include conventional water treatment. or just disinfection in the case of Carrizo water. Distribution costs will be based on costs as estimated in previous studies for delivery to the SAWS system. Other use includes demand reduction hy conservation, reclaimed water reuse, transfer of water through purchase or lease, and treatment of brackish water by demineralization.

W:\07755001\SUMMAAY.TBL Page 2 of 2 TREATMENT AND DISTRIBUTION ALTERNATIVES IN VOLUME 3

®® 0 U) 0 0 FIRM WATER Cl) ~ U) 0 U) SUPPLY(!) N ~ Ill. ... "!. "! ...... LD ,...Cl) ...,... (ACFT/YR) Is N NOTES: -----.. 1,500 FOR DESCRIPTION OF EACH ALTERNATIVE SEE TABLE ES-11.

w0:::: - 1- 1,000 I ,., {!) WATER SUPPLY VALUES FOR EACH ~ - ALTERNATIVE ARE ON A STAND u.l=' - ALONE BASIS AND CANNOT, IN ou. MANY CASES, BE ADDED TO OTHER 1-u - cn

NOTE: TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA ALTERNATIVES G-23, G-24, G-25 AND G-26 (ALTERNATIVE SUPPLIES FOR GBRA PLANNING AREAS) ARE COSTS OF TREATED WATER DELIVERED ON A WHOLESALE BASIS AND DO NOT INCLUDE THE OPERATING COSTS OF THE DISTRIBUTION SYSTEM. THE ALTERNATIVES INCLUDE COSTS TO MEET PEAK SUMMARY OF UNIT COSTS AND FIRM DEMANDS AND ARE TYPICALLY HIGHER COMPARED TO ALTERNATIVES IN WATER SUPPLY FOR TREATMENT VOLUME 2, WHICH ARE MOSTLY LARGER PROJECTS WITH UNIFORM ANNUAL lil~ DELIVERY RATES. AND DISTRIBUTION ALTERNATIVES HDR Engineering, Inc. IN VOLUME 3 FIGURE ES -12A APPENDIX F

SAWS PROPOSED WATER RESOURCE PLAN Appendix F San Antonio Water System Proposed Water Resource Plan

In April, 1994, the San Antonio Water System proposed a regional water resources plan1 (SAWS plan) as a framework from which to reduce the City's dependence on the Edwards Aquifer. The plan was formulated on five key items affecting the City's water supply and demand. Those key items are: Conservation Reuse of Reclaimed Water Lease of Irrigation Water Rights Acquisition of Guadalupe River Water by Trading Reclaimed Water Enhanced Recharge of the Aquifer

The SAWS plan involves several interrelated elements which could affect the availability and movement of water in both the Edwards Aquifer and throughout the Guadalupe - San Antonio River Basin. The San Antonio River Authority and the Guadalupe-Blanco River Authority joined with SAWS in requesting an engineering and environmental evaluation of portions of the plan at the same reconnaissance level as other Phase I alternatives. The following is an overview of some of the key elements of the plan.

Aquifer Demand Management A key component of the plan is an Edwards Aquifer demand management plan that, if implemented, would reduce both annual and seasonal peak pumpage resulting in increases in springflows. The SAWS plan assumes that Senate Bill 147?2 (or an equivalent bill) will eventually be put in place, thereby regulating Edwards Aquifer water production through wells which would contribute toward increasing springflows. The SAWS plan proposes a coordinated program of reducing per capita water use through water conservation, reduction in demand for aquifer water by substituting reclaimed water for some uses, and leasing of irrigation rights.

1Proposed Water Resource Plan prepared by the San Antonio Water System and presented to the San Antonio Mayor's 2050 Water Resources Committee, April 27, 1994.

2Senate Bill 1477, 1993 Texas Legislature, creating the Edwards Aquifer Authority with jurisdiction to regulate aquifer usage in Uvalde, Medina, Bexar counties, and parts of Atascosa, Carnal, Guadalupe, Hays, and Caldwell counties. At the time of this report the creation of the Edwards Aquifer Authority is still in question as various legal issues regarding its creation are unresolved.

F-1 Reclaimed water use would be implemented throughout the year to reduce base loads, while demands during periods of reduced springflows would be reduced by stringent conservation practices. Water demands would be controlled through a regional authority regulating groundwater pumpage for municipal and irrigation use such as envisioned in SB 1477. By implementing the aquifer management elements of the SAWS plan, it has been estimated that total aquifer pumpage could be reduced to 368,000 acft/yr, which is eight percent below the year 2008 limit of 400,000 acft/yr contained in SB 1477. Table F-1 contains a possible allocation of aquifer pumpage among the major aquifer users for a total annual pumpage of 400,000 acft/yr as allowed by SB 1477 based on percentages of uses as occurred in 1989. The distribution shown in Table F-1 for total aquifer pumpage was used in the Phase 1 studies. Table F-2 contains the SAWS alternative aquifer pumping scenario with a total annual pumpage of about 368,000 acft/yr. The SAWS pumpage scenario has been used in the Phase 1 analyses to estimate total aquifer pumpage and is frequently referred to as the "SAWS 368,000 acft/yr aquifer pumpage scenario" or "SAWS aquifer pumpage scenario." Changes under this . plan (as compared to the 400,000 acft/yr baseline scenario) included an increase in SAWS proposed annual pumpage from 139,165 acft/yr to 157,320 acft/yr an increase of 18,155 acft/yr ( 13 percent) with a corresponding leveling of SAWS monthly demands so that SAWS summer demands are reduced by as much as 15 percent or 2,392 acft/month in August. (Note: . Historically, SAWS peak annual pumpage was 176,600 acft (1989) with a peak monthly pumpage of 18,622 acft.) The higher SAWS annual pumpage under their 368,000 acft/yr plan is more than offset by SAWS leasing of irrigation pumpage rights totalling 50,000 acft/yr (i.e., 20,000 acft/yr in Uvalde County and 30,000 acft/yr in Medina County). Additionally, the SAWS plan includes the construction of four new recharge structures in the Nueces River Basin which would increase average annual recharge to the aquifer by about 45,000 acft/yr and average drought recharge by about 9,000 acft/yr (see Table F-3). Annual water use by other aquifer users was assumed to remain constant at 120,405 acft/yr in both pumpage scenarios. Figure F-1 shows a comparison of total monthly aquifer pumpage for the 400,000 acft/yr scenario and the 368,000 acft/yr scenario with stacked bars for each type of water use.

F-2 Table F-1 EDWARDS AQUIFER BASELINE PUMPAGE SCENARIO - 400,000 ACFT/YR TOTAL MONTH SAWS UVALDE CO. MEDINA CO. TOTAL AQUIFER PUMP AGE IRRIGATORS IRRIGATORS IRRIGATORS OTHERS PUMPAGE JAN 8515 3758 1859 5617 8262 22394 FEB 7567 1880 929 2809 7901 18277 MAR 9702 7516 2789 10305 9041 29048 APR 11118 6577 3254 9831 9585 30534 MAY 13297 5637 4647 10284 10700 34281 JUN 12689 14092 6971 21063 11196 44948 JUL 15360 17850 6506 24356 12421 52137 AUG 15731 14092 8366 22458 12527 50716 SEP 13492 10334 5112 15446 11411 40349 OCT 12101 7516 3718 11234 10217 33552 NOV 9398 2818 1394 4212 8359 21969 DEC 10195 1880 929 2809 8785 21789

TOTAL 139165 93950 46474 140424 120405 399994

Table F-2 SAWS ALTERNATIVE EDWARDS AQUIFER PUMPAGE SCENARIO - 368,000 ACFT/YR TOTAL MONTH SAWS UVALDE CO. MEDINA CO. TOTAL OTHERS AQUIFER PUMP AGE IRRIGATORS IRRIGATORS IRRIGATORS PUMPAGE JAN 12928 2958 659 3617 8262 24807 FEB 11550 1479 329 1808 7901 21259 MAR 13339 5916 989 6905 9041 29285 APR 13202 5176 1154 6330 9585 29117 MAY 13339 4437 1647 6084 10700 30123 JUN 13202 11092 2471 13563 11196 37961 JUL 13339 14050 2306 16356 12421 42116 AUG 13339 11092 2966 14058 12527 39924 SEP 13202 8134 1812 9946 11411 34559 OCT 13339 5916 1318 7234 10217 30790 NOV 13202 2218 494 2712 8359 24273 DEC 13339 1479 329 1808 8785 23932

TOTAL 157320 73947 16474 90421 120405 368146

F-3 Table F-3 Summary of Recharge Enhancement Projects

Average Conditions Drought Conditions

Cost/Unit Cost/Unit Recharge Recharge Recharge Recharge Surface Annual Enhance- Enhance- Enhance- Enhance- Recharge Capacity Area Cost ment ment ment ment Project (acft) (ac) ($) (acft/yr) ($/acft/yr) (acft/yr) ($/acft/yr)

Lower Sabinal 8,750 454 I ,335,379 16.442 XI 2.358 566 Lower Verde 3,600 334 590,084 4,850 122 1,719 343 Lower Hondo 2,800 232 1,218,701 6,779 180 I ,193 1,022 Lower Frio 17 500 I 099 3 258 211 17 064 191 3 980 819 Total 32,650 2,119 6,402,375 45,135 9,250 Average 142 692

'Program includes projects with a Cost/Unit Recharge Enhancement for Average Conditions less than $192/acftlyr ($0.59/1,000 gallons).

Springflow The SAWS aquifer pumpage scenario was incorporated into the TWDB Edwards Aquifer Model to obtain estimates of springflow at Comal, San Marcos, and other springs. The results of the simulated springflows from the TWDB Edwards Aquifer Model for all pumpage scenarios were adjusted to account for the difference in the model's simulated historical springflows and observed springflows. Compared to the 400,000 acft/yr pumpage scenario, Coma! springflows would increase by an average of about 46 cfs over the entire 1934-89 period simulated and about 29 cfs during the 1947-56 drought period. Figure F-2 compares simulated Coma! springflow during the 1947-56 critical drought period for the 400,000 acft/yr aquifer pumpage scenario and SAWS plan pumpage of 368,000 acft/yr. Figure F-3 shows the average monthly increase in Comal springflow resulting from the decrease in aquifer pumpage from the 400,000 acft/yr scenario to the 368,000 acft/yr scenario plotted at the same scale as Figure F-1. Figure F-4 presents estimated San Marcos springflow for the 400,000 acft/yr aquifer pumpage scenario and SAWS plan pumpage of 368,000 acft/yr.

Water Trades The aquifer demand management plan proposed by SAWS places a uniform monthly pumping load on the aquifer for municipal use that requires peak municipal water demands to be

F-4 met from other sources. To meet the peak demands, the SAWS plan would divert surface water from the Guadalupe River possibly near Lake Dunlap or Gonzales. Water potentially available from several sources would be diverted throughout the year but mostly during summer peak demand months for delivery to the San Antonio area. The water potentially available includes possible run-of-the-river water and stored water transfers from the Central Power & Light Coleto Creek electric generating station, from GBRA water rights associated with the Calhoun Canal Division, and stored water from Canyon Lake. To mitigate for the water rights transferred from the Coleto Creek project and potentially the Calhoun Canal, the SAWS plan proposes to transfer San Antonio reclaimed water down the San Antonio River to Goliad and then divert it to Coleto Creek Reservoir as make-up water for cooling purposes. (Note: In the SAWS Proposed Water Resource Plan, the Applewhite Reservoir was originally part of a storage and delivery system to utilize reclaimed water and would have increased the quantity of firm water available to potential downstream users. However, after the failure of the Applewhite referendum in August, 1994, Applewhite Reservoir was removed from further study.) In the Phase 1 analyses for this Volume 3 report (which were performed after the failure of the Applewhite referendum), reuse of reclaimed water within the Bexar County area was limited to 18,000 acft/yr for the tunnel reuse project, and to requirements for make-up water at Braunig and Calaveras Reservoirs.

F-5 6o,ooo r--1-1--~---r--r--~-----,-----.--.,----.------,-----,

50,000

..-. :I: 1- ~ 40,000 p~ u. ' ~· 30,000 ...... w (!)

10,000

0 I I JAN I I I FEB I I I MAR I I I APR I I I MAv' I I JUN I I I JUL I I I AUG I I I SEP I I I OCT I I I NOV I I I DEC I I MONTH

0 OTHERS • SAWS II IRRIGATORS TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA

1 -Monthly demands lor 400,000 ac-ft!year baseline demand COMPARISON OF EDWARDS 2- Monthly demands lor 368,000 ac-ftlyear demand based on SAWS plan) Hl~ AQUIFER PUMPAGE PLANS - ALL USES HDR Engineering, Inc. FIGURE F-1 350

300

250

(/)- t 200 s:-- 0 u. 1so az 0:: (/)Q.. 100

0 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 YEAR --· 400,000 AC-FTNR PUMPAGE BASELINE TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA SAWS PLAN

NOTE: COMAL SPRINGFLOW THE RESULTS OF THE SIMULATED SPRINGFLOWS FROM THE TWDB COMPARISON FOR ALTERNATE EDWARDS AQUIFER MODEL WERE ADJUSTED TO ACCOUNT FOR THE 1-il~ DIFFERENCE IN THE MODEL'S SIMULATED HISTORICAL SPRINGFLOWS HDR Engineering, Inc. PUMPAGE PLANS AND OBSERVED SPRINGFLOWS. FIGURE F-2 --- 60,000 - - ..... - 1-u.. I 0 ---'------

TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA

INCREASES IN COMAL SAWS Plan vs_ 400,000 ac-ftlyr pumpage baseline averages based on 1947-56 period. 1-il~ SPRINGFLOW WITH SAWS PLAN HDR Engineering, Inc. FIGURE F-3 350 -

300 - - - ! -

250 - ...... - ~ 0 =\.. ~ 200 I 0 u. ..J ~ 150 \ ' 0:: a.. en ·\~ ... I ~N \ 100 - - ~ "~v \J \r' IVV\ ~~ LJV ~ ~ ,II! 50 - \,/ - - 0 .. L____ 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 YEAR 400,000 AC-FTNR PUMPAGE BASELINE TRANS TEXAS WATER PROGRAM I SAWS PLAN WEST CENTRAL STUDY AREA

NOTE: SAN MARCOS SPRINGFLOW THE RESULTS OF THE SIMULATED SPRINGFLOWS FROM THE TWDB 1-il~ COMPARISON FOR ALTERNATE EDWARDS AQUIFER MODEL WERE ADJUSTED TO ACCOUNT FOR THE PUMPAGE PLANS DIFFERENCE IN THE MODEL'S SIMULATED HISTORICAL SPRINGFLOWS HDR Engineering, Inc. AND OBSERVED SPRINGFLOWS. FIGURE F-4 THIS PAGE INTENTIONALLY LEFT BLANK.

F-10 APPENDIX G

CANYON LAKE FIRM YIELD Appendix G

Canyon Lake Firm Yield

Introduction

The calculation of the firm yield of Canyon Lake is a complex function of many interrelated factors and assumptions including hydropower subordination, Edwards Aquifer pumpage and resultant springflow, reservoir operation policy, point(s) of diversion, and channel losses incurred in delivery of water for a variety of types of use. All of these factors are in addition to the basic, highly variable hydrologic factors of inflow and net evaporation. The firm yield of Canyon Lake is dependent on senior water right requirements and streamflows below the lake which requires the use of a model with the capability to simulate basin-wide conditions. The Guadalupe- San Antonio River Basin ModeP (GSA Model), which has the capability to simulate basin-wide streamflow conditions, was modified and utilized to compute the firm yield of Canyon Lake.

Guadalupe - San Antonio River Basin Model The GSA Model was originally created as part of a study to evaluate Edwards Aquifer recharge and the potential for recharge enhancement projects in the Guadalupe - San Antonio River Basin. The primary objective of the original model was to determine water available for new recharge enhancement projects which would be junior in priority to all other existing water rights in the basin. The original model had the capability to simulate existing reservoirs in the river basin, including Canyon Lake, and to simulate streamflow conditions for various Edwards Aquifer pumpage and resultant springflow scenarios. The GSA Model employs a monthly time step proceeding with flow calculations in an upstream to downstream order simulating recharge, channel losses, water rights, return flows, and reservoir operations. Changes in upstream flow from the natural flow at each

1 HDR Engineering, Inc., "Guadalupe- San Antonio River Basin Recharge Enhancement Study," Volumes I, II, and III, Edwards Underground Water District, September, 1993.

G-1 model control point are translated to the next downstream control point using delivery equations specified for each stream segment. Calculations are performed at each of the 38 watershed control points located throughout the river basin as shown in Figure G-1 beginning in the headwaters of the Guadalupe River near Comfort (ID# 1670), continuing downstream to Victoria (ID# 1765), moving to the headwaters of the San Antonio River Basin near Medina Lake (ID# 1795), continuing downstream to Goliad (ID# 1885), and finally combining flows from both the Guadalupe and San Antonio Rivers at the Saltwater Barrier near Tivoli (ID# 1888). These control points were generally established at streamflow gaging stations, existing reservoirs, and other locations near the downstream limits of the Edwards Aquifer recharge zone. One of the most complicated aspects of GSA Model development was the determination of operational releases (inflow passage and/or releases from storage) at Canyon Lake necessary to satisfy senior water rights, contractual obligations, hydropower requirements, and Federal Energy Regulatory Commission (FERC) guidelines. There are five primary steps the model executes in order to determine monthly operational releases for Canyon Lake. Step 1: The first step is the calculation of required inflow passage or release for senior water rights (non-yield release). The release for senior water rights is limited to a maximum of the inflow to Canyon Lake.

Step 2: Once the non-yield release is determined, the model computes the yield release. The yield release may include both inflows and storage and represents the quantity of water which would have to be released to satisfy contractual obligations in full (with the exception of CP&L at Coleto Creek Reservoir which is delivered only as needed) and senior water rights to the extent they could be satisfied with the non-yield release. It is assumed that releases for contractual obligations must be sufficient to deliver full contracted amounts to the points of diversion so that any losses in delivery are included as part of the firm yield at Canyon Lake.

Step 3: The third step in the modeling of Canyon Lake operations is the calculation of inflow passage necessary to comply with FERC Guidelines. These guidelines specify instream flow minima of 100 cfs (June-January) and 120 cfs (February-May) to be maintained in non-drought conditions to the extent inflows, as measured at the USGS streamflow gage located near Spring Branch (ID# 1675), are available. In the event of 45 consecutive days of

G-2 SlREAMGAGES USED AS WA lEASHED CONTROl I"'INTS Dfl.t.IHAGE.... m• STREAM NAME. LOCAT10N ISO.MI.I PfRIOD OF RECORD N I 1670 GUADAll)P( R. COMFORT ., 6119 12/II!J 1675 GUADALUPE R , SPRING BRANCH 1315 7122 12189 1617 CANYON LAKE 1432 1162 12189 1685 GU.t.OALUPE R., ABOVE COMAL R Hill 1128-1211:19 1690 COMAL R., NEW BRAUNFELS 1128-12189 HOO SAN MARCOS SPR, SAN MARCOS .,."" 6156-12/1!19 1110 BLANCO R., WIMIIERLEY 7121-12119 1713 BlANCO R.. KYLE "' ti/56-12189 1720 SAN MAI'ICOS R.• lUliNG "',,. 6!39 121'89 1130 PLUM C., lULING ,., 4/l0-12189 1746 PEACH C., DILWORTH ... ll!i9-9/79 1750 SANOIES C., WfSTHOFf 8159-12189 1158 GUAOALUH fl .• CUERO 4934"' 9110-11135. 1164-12!19 1765 GUADALUf'£ R., VICTOAIA 5198 12/J.t-12/lt 1774 COLETO CfiEEK RESERVOIR ... 2180-12189 1780 SAN ANTONIO fl., SAN ANTONIO 41.8 3/l9-12fll9 1117 SALADO C., SAN ANTONIO. UPPER 10160-12189 1788 SALADO C., SAN ANTONIO, LOWEFI "' 10160-12189 1795 MEDINA LAKE "' •tt3-12119 1108 MEDINA A .• SOMEFISET '" tOnCH2/81 1815 MEDINA A., SAN ANTONIO 1317"' 1/31-12189 1818 SAN ANTONIO A .• ElMENOOflf 1143 10182-12181 1135 SAN ANTONIO A., FALLS CITY 2113 5125-12189 1839 CIBOLO C .. BOERNE ... 3/fi2-12189 1150 CIBOLO C.. SELMA •1•6-12189 1160 CIBOLO C., FALLS CITY "' 10130-12189 1165 ECLETO C .. FIUNGE "' 4/Ei:Z-12/81 1185 SAN ANTONIO A., GOLIAD 3921"' 3139-12189 1188 GUADALUPE A., TIVOli 10128 9/fiS-12181

ITREAMGAQU USED AS SIECONDAIIY CONTROl POINTS

1878 GUADALUPE A., SATTUA 3160--12189 1189 COUTO C., Soti!OEDEA '"'m 1017.. 12181 1770 COl&TO C., Stw!OEOER 10112-ln& 1716 COL£1'0 C .. YICTOfiiA ...''" 7139-t/5-4, Bnl-12111 1788.8 MEDINA A .. IANOEAA m 101112-12181 1790 M£OirrfA Fl., I'll'£ CFIEEK 10122--6136. 101&2-1112 Cl 1711 fifO llt..1JFf C .. N'E CM:EK 56.3 I "' 4/H-11181 1000 MEDINA CANAL •122 ...13-4, 71&7-12181 ~ 1805 Mf:DINA A., AIOMEDINA "" 2153-tnJ 181-i HELOTES C., HELOTES '" 8/el-12/81 1825 CALAVERAS C .. ELMENDORF 17.2" 10JS4.-Int WATVtSHEO COtfnlQl rowTS WITHOUT STREAMOAOU

LAX£ W000 IH-6) 2103 1180--12111 OlMOS C .. EDWARD$ ,, NIA ," DIVEFISION LAKE SUIWATERSHEO Ui.6 DEEP C., EDWARDS 13.1 ..."" "25 SAN GERONIMO C., EDWAADS 61.3 NIA ,. LEON C., EDWARDS 19.7 " IFIAUNIG LAIC£ .. 2163-12181"" CAlAVERAS LAKE til!i.O 1nt-1218t "G SINK. f'UAGATDFIY, YORK, .... .1 AND AUIGATOFI CAlUS "" LEGEND USGS Streamgage "' (Watershed Control Point)

USGS Slreamgage • (Secondary Control Point) Watershed Control Point lSJ (Wrthout Slreamgage)

TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA

WATERSHED CONTROL POINT 1-il~ AND STREAMGAGE LOCATION MAP HDR Engineering, Inc. FIGURE G-1 inflow less than 90 cfs, drought conditions apply and the instream flow requirement below Canyon Lake is reduced to passage of inflows up to 90 cfs until the reservoir level exceeds 909.0 ft-msl.

Step 4: The fourth step in the modeling of Canyon Lake operations is calculation of inflow passage for hydropower generation (hydro release). The GSA Model determines the Canyon Lake inflow passage necessary to maintain a specific flowrate at Lake Dunlap. Flows at Lake Dunlap are based on the sum of the monthly flows at control points on the Guadalupe and Carnal Rivers near New Braunfels. No releases from Canyon Lake storage are made strictly for the purposes of hydropower generation.

Step 5: Ultimately, the maximum of the yield, FERC, and hydro release is selected as the monthly operational release from Canyon Lake and flows are simulated at all control points throughout the river basin.

The original GSA Model was adequate for computing water potentially available for recharge enhancement or other purposes using the monthly time step. However, for computing Canyon Lake firm yield, the monthly time step employed by the model did not adequately represent the daily variation of Canyon Lake operational releases. Therefore, a daily analysis of Canyon Lake inflows, specifically as they pertain to hydropower and FERC requirements, was necessary in order to obtain an accurate assessment of Canyon Lake operational releases.

GSA Model Enhancements and Assumptions A series of enhancements were introduced into the GSA Model in order to more accurately define the operational releases for Canyon Lake. These enhancements included:

• A revision to Canyon Lake inflow in September, 1952 to reflect the special circumstances related to one significant storm event.

• A daily analysis of Canyon Lake inflows using historical daily gaged flows at Spring Branch for determining inflow passage requirements for hydropower and FERC requirements.

• The capability to specify the diversion of Canyon Lake firm yield at any control point downstream of Canyon Lake.

G-4 • An iterative solution process for calculating the Canyon Lake firm yield.

• A revision to the makeup diversion simulation for Coleta Creek Reservoir to include special provisions included in the CP&L run-of-the-river water right and Canyon Lake contract.

• Updated existing Canyon Lake contracts and water rights in the Guadalupe - San Antonio River Basin.

The monthly inflow to Canyon Lake in September, 1952 was revised in the GSA Model to reflect the special circumstances surrounding this major storm event. The accuracy of defining this event is particularly important because of its occurrence during the critical drought and because of its direct effect on the firm yield of Canyon Lake. Estimates of Canyon Lake inflow prior to July, 1962 were based on a regression equation using flows for the Guadalupe River at Spring Branch (ID# 1675) and potential intervening runoff between Spring Branch and Canyon Dam as independent variables. The coefficient of determination for this regression equation which was based on actual Canyon Lake inflow computed by mass balance for the July, 1962 through December, 1989 period is 0.99 indicating that 99 percent of the variation in Canyon Lake inflow can be explained by the equation. It was discovered, however, that the regression equation provided a less than adequate estimate of Canyon Lake inflow for the flood event which occurred in September, 1952 due, in large part, to the concentration of unusually intense precipitation downstream of the Spring Branch gage. An alternative method which incorporated measured runoff between Spring Branch and New Braunfels as well as differences in areal precipitation and soil cover complex above and below Canyon Dam was utilized to compute the revised Canyon Lake inflow for this month. The revised Canyon Lake natural inflow for September, 1952 is 163,596 acft and is apprc'lximately 30,000 acft greater than the original estimate. A daily analysis of Canyon Lake inflows using historical gaged flows at Spring Branch was incorporated into the GSA Model to more accurately determine required inflow passage for hydropower and FERC requirements. Daily inflow to Canyon Lake was computed using the total monthly inflow, which includes adjustments for upstream water rights and return flows, and disaggregating it using the daily distribution of monthly flows as measured at the

G-5 Spring Branch gage. The monthly volume of inflow required to be passed for downstream senior water rights is distributed on a daily time step based on the pattern of inflow for the month. The monthly volume for releases of storage to meet contractual obligations was assumed to occur uniformly throughout the month. Passage of daily inflow as required by FERC was determined using the daily flow at Spring Branch directly as specified by FERC. Downstream hydropower requirements at Lake Dunlap for passage of daily inflow were based on the total monthly flow for the Guadalupe and Coma! Rivers at New Braunfels. The total monthly flow at this location was assumed to occur uniformly during the month and a daily deficit for hydropower was determined as the difference between the flow requirement at Lake Dunlap (i.e. 365 cfs, 600 cfs, etc.) and the combined daily flow for the Guadalupe and Coma! Rivers at New Braunfels. Any deficits for hydropower were satisfied to the extent possible by passage of Canyon Lake inflow. The required operational releases computed on the daily time step were summed to a total monthly operational release for Canyon Lake. The monthly total was used by the model to simulate monthly flows at all control points in the river basin. A graphical example of this daily analysis of Canyon Lake inflows is shown in Figure G-2. The capability to specify the diversion point for Canyon Lake firm yield at any control point at or downstream of Canyon Lake was incorporated into the GSA Model. This modification was accomplished by specifying the Canyon Lake firm yield as a contractual obligation with a municipal type monthly demand distribution. This feature allowed the model to account for the required operational releases to meet demands at a downstream control point including delivery losses. An iterative solution process for calculating the Canyon Lake firm yield was included in the model. The half-interval method was used for solving for the firm yield of Canyon Lake at any control point at or downstream of Canyon Lake. The methodology for modelling the makeup diversion from the Guadalupe River for Coleta Creek Reservoir under CP&L's run-of-the-river water right and Canyon Lake contract was revised to more accurately model the specific provisions in the water right and contract. CP&L currently holds a 20,000 acft/yr run-of-the-river water right diverted from the Guadalupe River near Victoria. This water right is senior to Canyon Lake but junior

G-6 700 ---,----

600

500 en -u.. -(.) 400 300 u..~ z HYDROPOWER RELEASE_m:MANQ_ __ _ 200 0 -.1 SENIOR WATER RIGHTS RELEASE 100

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

DAY

TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA

CANYON LAKE lil~ DAILY INFLOW ANALYSIS HDR Engineering, Inc. FIGURE G-2 to those water rights associated with the Calhoun Canal Division at the Saltwater Barrier. The priority of the Calhoun Canal Division water rights with respect to the CP&L run-of the-river water right was incorporated into the GSA Model so that, if a deficit existed at the Saltwater Barrier, no diversion under CP&L's water right could take place. Several provisions exist in the Canyon Lake contract for cooling water makeup diversions to Coleta Creek Reservoir. Diversion of stored water from Canyon Lake released for makeup at Coleta Creek Reservoir occurs at the same diversion point, using the same facilities, as CP&L's run-of-the-river water right. Makeup needs for Coleto Creek Reservoir are computed each month with makeup demands met to the extent possible from the run-of the-river water right. If makeup demands cannot be satisfied from the run-of-the-river water right, then they are met from the Canyon Lake contract subject to the provisions of the contract. There are two provisions in the Canyon Lake contract for Coleto Creek Reservoir which limit makeup diversions under the contract which were incorporated into the GSA Model: 1) During any calendar year, the quantity of water to be released from Canyon Lake conservation storage and delivered to the diversion point shall not exceed 18,900 acft.

2) During any five consecutive calendar-year period, no more than 30,000 acft from Canyon Lake conservation storage shall be delivered to the diversion point.

Water rights and Canyon Lake contracts were updated in the model. Recent Canyon Lake contracts and amendments to existing contracts were included as well as new water rights. New water rights include 20,000 acft/yr for municipal use by the City of Victoria to be taken from the Guadalupe River near Victoria. The SAWS/SARA Tunnel Reuse Project, which is expected to divert SAWS return flows and consume approximately 18,000 acft/yr in accordance with a typical monthly demand pattern for irrigation use, was also included.

G-8 Comparison of Canyon Lake Firm Yield Results Comparisons were made of Canyon Lake firm yield computed using the GSA Model

2 to those presented by EH&A • Based on historical springflows and diversion of Canyon Lake firm yield near New Braunfels, comparable total yield estimates for various hydropower requirements at Lake Dunlap are summarized in Table G-1. The maximum difference in the firm yield estimates was about nine percent. In general, differences between HDR and EH&A yield estimates can be attributed to minor differences in drought inflows and to the GSA Model accounting for channel losses which were not addressed by EH&A.

Table G-1 Comparison of Canyon Lake Firm Yield Estimates HDR EH&A Hydropower Canyon Lake Canyon Lake Flow Requirement Firm Yield1 Firm Yield1 Percent at Lake Dunlap (acft/yr) (acft/yr) Difference 600 cfs 47,400 50,000 5.5% 365 cfs 60,500 66,000 9.1% 0 cfs 94,400 86,000 -8.9%

Note: 1) Firm yield estimates based on historical springflows with diversion of all flrm yield assumed to occur near New Braunfels.

Canyon Lake Firm Yield Estimates The firm yield of Canyon Lake was computed for various combinations of Edwards Aquifer pumpage scenarios, hydropower requirements, and points of diversion. Three Edwards Aquifer pumpage scenarios were considered including pumpage of 200,000 acftjyr, 368,000 acft/yr, and 400,000 acft/yr. The results of the simulated springflows from the TWDB Edwards Aquifer Model for all pumpage scenarios were adjusted to account for the

Espey, Huston & Associates, Inc .• "Engineering Analyses and Hydrologic Modeling to Determine the Effects of Subordination of Hydropower Water Rights," Guadalupe-Blanco River Authority, March, 1993.

G-9 difference in the model's simulated historical springflows and observed springflows. Two hydropower requirements at Lake Dunlap, 0 cfs and 365 cfs, were considered. Firm yield was computed for each of the Edwards Aquifer pumpage scenarios for both hydropower requirements and for three points of diversion. The three points of diversion included Canyon Lake, Lake Dunlap, and near Gonzales. Several contracts have been signed between GBRA and various entities for water supply from Canyon Lake. These contracts divert their portions of the Canyon Lake firm yield at various locations downstream of Canyon Lake. The point of diversion and total demand for each of these contracts impacts the operational releases and remaining firm yield of Canyon Lake. Therefore, the firm yield of Canyon Lake computed was separated into two components: the "committed yield" and the "uncommitted yield." The committed yield is the amount of Canyon Lake firm yield already obligated through contracts having specified points of diversion. The uncommitted yield is the amount of Canyon Lake firm yield computed to be available at a particular point of diversion in addition to the amount that has already been committed by existing Canyon Lake contracts totalling 38,438 acft/yr. The combined total of committed and uncommitted firm yield is the total firm yield for Canyon Lake. A summary of existing Canyon Lake contracts and their annual diversion rates used in this study is provided in Table G-2. Due to the consideration of scenarios involving the subordination of hydropower water rights from the current level of 600 cfs at Lake Dunlap to 365 cfs and 0 cfs, various assumptions regarding downstream water rights were required. Water rights which are presently junior in priority to Canyon Lake are for the most part satisfied by Canyon Lake inflows because of the 600 cfs hydropower flow requirement. Further subordination of hydropower to Canyon Lake firm yield would involve the conversion of a non-consumptive use (hydropower) to a consumptive use (Canyon Lake firm yield). Therefore, water rights downstream of Lake Dunlap which are presently junior to Canyon Lake (total of 23,471 acft/yr) were considered as senior water riglrts in the GSA Model for scenarios involving hydropower subordination in order to insure that these rights were met by passage of Canyon Lake inflows to the extent which they would have been based on a 600 cfs

G-10 Table G-2 Summary of Canvon Lake Contracts Annual TyOe of Diversion GSA Model Contract Owner se (acft/yr) Diversion Point Henk Paving Company, Inc. Industrial 1 Canyon Lake Goldbeck Irrigation 1 Canyon Lake Cunningham Irrigation 2 Canyon Lake Kleck Municipal 1 Canyon Lake Propst Municipal 1 Canyon Lake Salge Municipal 1 Canyon Lake Welch Municipal 1 Canyon Lake DuBose Municipal 2 Canyon Lake Stanaland Municipal 2 Canyon Lake Yacht Club Municipal 4 Canyon Lake Comal County Fair Assoc., Inc. Industrial 1 Lake Dunlap Southbank Property Owners Assoc. Irrigation 1 Lake Dunlap Comal lSD Irrigation 2 Lake Dunlap Cooper Irrigation 2 Lake Dunlap Zurovec Irrigation 4 Lake Dunlap Erben Irrigation 5 Lake Dunlap Whitewater Sports Municipal 1 Lake Dunlap Maricopa Lodge Municipal 5 Lake Dunlap Murrell Municipal 10 Lake Dunlap Crystal Clear WSC Municipal 500 Lake Dunlap Southwest Texas State University Municipal 500 Lake Dunlap City of San Marcos Municipal 5,000 Lake Dunlap New Braunfels Utilities Municipal 6,720 Lake Dunlap Canyon Regional Water Authority* Municipal 8,740 Lake Dunlap ACME Brick Company Industrial 25 Lake Wood Standard Gypsum Corp. Industrial 140 Lake Wood Structural Metals, Inc. Industrial 600 Lake Wood Ind. Golf Assn. Irrigation 2 Lake Wood Missildine Irrigation 10 Lake Wood Chapparal Country Club, Ltd. Irrigation 15 Lake Wood Gonzales County WSC Municipal 700 Lake Wood Springs Hill WSC Municipal 1,500 Lake Wood City of Seguin Municipal 2,000 Lake Wood DuBose Industrial 5 Cuero Central Power & Light Industrial 6,000 Victoria ISP Tech Industrial 40 Saltwater Barrier Carbon Graphite Industrial 334 Saltwater Barrier BP Chemicals, Inc. Industrial 1,100 Saltwater Barrier Union Carbide C&P Industrial 2,400 Saltwater Barrier Calhoun County Rural WSC Municipal 560 Saltwater Barrier Citv of Port Lavaca Municipal 1 500 Saltwater Barrier Total 38,438 *Pending

G-11 hydropower requirement. Summaries· of uncommitted and total Canyon Lake firm yield for various combinations of Edwards Aquifer pumpage, hydropower subordination, and point of diversion are presented in Table G-3 and Figure G-3. For hydropower subordination to 365 cfs, a dramatic decrease in firm yield occurs from an Edwards Aquifer pumpage scenario of 200.000 acft/yr to 368,000 acft/yr and 400,000 acft/yr. This large decrease in firm yield is primarily due to significant reductions in t1ow from Coma! Springs which contributes to the hydropower requirements at Lake Dunlap. This reduction in t1ow from Coma! Springs requires more frequent and larger passages of Canyon Lake int1ow to satisfy hydropower requirements. thereby decreasing the firm yield of Canyon Lake. For hydropower subordination to 0 cfs, the decrease in firm yield for the various Edwards Aquifer pumpage scenarios is not as dramatic. When the hydropower requirement is reduced to 0 cfs at Lake Dunlap, Canyon Lake int1ow passages are dependent on senior water rights and FERC requirements, and the impact of the reduction in springt1ow is not as prominent. The point of diversion of the uncommitted firm yield int1uences the total Canyon Lake firm yield available. For a hydropower scenario of 365 cfs, the diversion of uncommitted firm yield at Gonzales provides the greatest firm yield. Diversion of the uncommitted firm yield at Gonzales is subject to some delivery losses from Canyon Lake to Gonzales and the estimated losses are included in the yield analysis. More importantly, however, the Gonzales diversion takes advantage of using yield releases to contribute toward meeting hydropower and FERC requirements. By using yield releases to contribute toward satisfying hydropower and FERC requirements, the amount of Canyon Lake int1ow that can be stored is increased translating into an increase in firm yield. On the other hand, diversion of the uncommitted firm yield directly from Canyon Lake does not take advantage of utilizing yield releases from Canyon Lake to meet hydropower or FERC requirements and, therefore, produces the least firm yield. Diversion of the firm yield at Lake Dunlap does not take advantage of utilizing yield releases to contribute toward satisfying hydropower requirements, but it does utilize yield releases to contribute toward satisfying FERC requirements. For subordination of hydropower to 0 cfs, the optimal location for diversion of uncommitted firm yield is Lake Dunlap. Diversion of the uncommitted firm yield at Lake Dunlap takes advantage of using yield releases to meet FERC requirements and, at the same time, minimizes delivery losses. Although diversion of the uncommitted firm yield

G-12 ------Table G-3 Summary of Canyon Lake Firm Yield Results

Canyon Lake Lake Dunlap Gonzales Diversion Point Diversion Point Diversion Point

Aquifer Uncommitted Total Uncommitted Total Uncommitted Total I Demand Hydropower Firm Yield2 Firm Yield3 Firm Yield2 Firm Yield3 Firm Yield2 Firm Yield3 Scenario3 Scenario1 (acft/yr) (acft/yr) (acft/yr) (acft/yr) (acft/yr) (acft/yr)

200,000 365 cfs 20,000 58,400 21,200 59,600 24,700 63,100 acft/yr 0 cfs 42,300 90,700 49,600 88,000 43,300 81,700

0 368,000 365 cfs 8,300 46,700 8,500 46,900 8,100 46,500 ...... ' w acft/yr 0 cfs 37,400 75,800 43,800 82,200 38,400 76,800

400,000 365 cfs 6,500 44,900 6,600 45,000 6,100 44,500 acft/yr 0 cfs 36,700 75,100 43,100 81,500 37,800 76,200

Notes: I) Hydropower Scenario represents the desired flowrate for power generation at Lake Dunlap. Both hydropower scenarios imply subordination of Guadalupe-Blanco River Authority hydropower rights to Canyon Lake. 2) Uncommitted f1111l yield is the portion of the total f1111l yield of Canyon Lake which has not been contractually committed. Existing contracts total 38,438 acft/yr assuming an average of 6,000 acft/yr delivered to Central Power & Light Company at Coleta Creek Reservoir. Results are presented for diversion of the uncommitted f1111l yield directly from Canyon Lake, from Lake Dunlap near New Braunfels, or from the Guadalupe River below the San Marcos River confluence near Gonzales. 3) Total finn yield is the sum of the uncommitted f1111l yield and existing contracts (38,438 acft/yr).

4) The results of the simulated springflows from the TWDB Edwards Aquifer Model for all pumpage scenarios were adjusted to account for the difference in the model's I simulated historical springflows and observed springflows. AQUIFER DEMAND SCENARIO: 200, 000 ACFT/YR AQUIFER DEMAND SCENARIO: 368,000 ACFT/YR (SAWS 2050)

50,000 Ci' ~ 45,000 E 45.000 ~ 40,000 ~ 40.000 '!-----~~~~~ 9 36,000 36,000 w w9 > 30,000 > 30.000 :::E a: 26,000 ~ 25,000 u:: u:: 0 20,000 0 ~ 15,000 ~ 15,000 :::E 5i! 10,000 ::E 10,000 5,000 5,000 8z 8z -l ::::> 0 ::::> 0

HYDROPOWER SCENARIO HYDROPOWER SCENARIO

AQUIFER DEMAND SCENARIO: 400,000 ACFT/YR

50,000~-- DIVERSION POINT 45,000 ~ • CANYON LAKE ~ 40,000 30.000 ~ LAKE DUNLAP 9w > 30,000 []GONZALES :::E a: 26,000 u:: 0 20,000 ~ 15,000 :i :::E 10,000 5,000 8z ::::> 0 TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA HYDROPOWER SCENARIO NOTE: CANYON LAKE THE RESULTS OF THE SIMULATED SPRINGFLOWS FROM THE TWDB UNCOMMITTED FIRM YIELD SUMMARY EDWARDS AQUIFER MODEL WERE ADJUSTED TO ACCOUNT FOR THE Hl~ DIFFERENCE IN THE MODEL'S SIMULATED HISTORICAL SPRINGFLOWS AND OBSERVED SPRINGFLOWS. HDR Engineering, Inc. FIGURE G-3 cfs hydropower scenario also takes advantage of usmg yield releases to meet FERC requirements, the greater delivery losses to Gonzales appear to result in an overall decrease in the total firm yield when compared to the Lake Dunlap diversion point. The impact of utilizing SAWS return flows to meet the makeup demands of Braunig, Calaveras, and Coleto Creek Reservoirs on the firm yield of Canyon Lake was analyzed. The quantity of water potentially available from conversion of CP&L's Canyon Lake contract and run-of-the-river water right to Canyon Lake firm yield was also estimated. For these analyses, only a scenario including hydropower subordination to 0 cfs and Edwards Aquifer pumpage of 368,000 acft/yr was considered. As shown in Table G-4, the impact of excluding SAWS return flows on the firm yield of Canyon Lake is a reduction of 3,200 acft/yr at the Lake Dunlap diversion point or 2,800 acft/yr at the Gonzales diversion point. These analyses also showed that conversion of CP&L's Canyon Lake contract (used for makeup diversion to Coleto Creek Reservoir) to firm yield diverted at Lake Dunlap or Gonzales would increase the uncommitted firm yield by 6,300 acft/yr or 5,600 acft/yr, respectively. Conversion of CP&L's water right near Victoria (20,000 acft/yr) to firm yield diverted at Lake Dunlap or Gonzales would add an additional 1, 900 acft/yr or 1, 600 acft/yr, respectively.

G-15 Table G-4 Summary of Canyon Lake Firm Yield Results Edwards Aquifer Pumpage Scenario of 368,000 acft/yr7 Hydropower Requirement of 0 cfs

Lake Dunlap Diversion Point Gonzales Diversion Point

Change in Change in Uncommitted Total Uncommitted Uncommitted Total Uncommitted Firm Yield Firm Yield Firm Yield Firm Yield Firm Yield Firm Yield Scenario (acft/yr)1 (acft/yr)2 (acft/yr) (acft/yr)1 (acft/yr)2 (acft/yr) SAWS Return Flows 43,800 82,200 ------38,400 76.800 ------Included3

SAWS Return Flows 40.600 79,000 -3,200 35,600 74,000 -2,800 Excluded4 Conversion of CP&L's 46,900 79,300 6,300 41,200 73,600 5,600 Coleto Creek Contract5 Transfer of CP&L's 48,800 81,200 1,900 42,800 75,200 1,600 Water Right'

Notes: l) Uncommined finn yield is the portion of the total finn yield of Canyon Like which has not been contractually commined. Existing contracts total 38.438 acftlyr assuming an average of 6,000 acftlyr delivered to Central Power & Light Company at Coleta Creek Reservoir. Results are presented for diversion of the uncommitted finn yield from Like Dunlap near New Braunfels and the Guadalupe River below the San Marcos River near Gonzales. 2) Total firm yield is the sum of the uncommined finn yield and existing contracts (38.438 acft/yr). When the CP&L Coleta Creek Reservoir contract is converted to Canyon Like !inn yield. the total existing contracts is reduced to 32.438 acftlyr. 3) Present conditions of SAWS return tlows in the San Antonio River contributing to streamtlow at the Saltwater Barrier. 4) Includes utilization of SAWS return tlows for meeting the makeup needs of Braunig, Calaveras. and Coleto Creek Reservoir. Assumes all SAWS return !lows are utilized. 5) Includes utilization of all SAWS return !lows and conversion of CP&L's Coleta Creek contract from Canyon Like to linn yield at Like Dunlap and Gonzales. 6) Includes utilization of all SAWS return !lows. conversion of CP&L's Coleta Creek contract from Canyon Like to finn yield. and transfer of CP&L's run of the river water right (20.000 acftlyr) to Canyon Like finn yield. 7) The results of the simulated springtlows from the 1WDB Edwards Aquifer Model for the pumpage scenario of 368.000 acftlyr were adjusted to account for the difference in the model's simulated historical spring flows and observed springtlows.

G-16 APPENDIX H

WATER RIGHTS TRANSFERS AND FIRM AVAILABILITY ANALYSES Appendix H Water Transfers and Firm Availability Analyses

Introduction One of the key aspects of a water plan recently proposed by the San Antonio Water System (SAWS) is the development of a surface water supply from the Guadalupe River to supplement available supplies from the Edwards Aquifer. It is envisioned that this surface water supply would be diverted from a point along the Guadalupe River near Lake Dunlap or near Gonzales and that the supply would be comprised of enhanced springflows (Appendix F), Canyon Lake firm yield (Appendix G), use of existing run-of-the-river water rights transferred upstream from the Saltwater Barrier near Tivoli, and possibly unappropriated water. Methods and assumptions applied and results obtained in the quantification of firm water availability from the combined utilization of these potential surface water sources are presented in this Appendix H.

Background and Assumptions The Guadalupe-Blanco River Authority (GBRA) has ownership interest in at least

SIX water rights associated with the Calhoun Canal Division which divert from the Guadalupe River downstream of the San Antonio River confluence and upstream of the Saltwater Barrier. These permits (Certificate of Adjudication Nos. 18-5173 through 18-5178) are senior to Canyon Lake and total about 172,500 acft/yr. Communications with GBRA indicate that up to 40,000 acft/yr might be made available for long-term in-basin and/or out-of-basin use and that up to an additional 40,000 acft/yr might potentially be made available for short-term or temporary use. Hence, 40,000 acft/yr (18,400 acft/yr municipal and 21,600 acft/yr industrial) and 80,000 acft/yr (36,800 acft/yr municipal and 43,200 acft/yr industrial) of the GBRA Calhoun Canal Division rights were selected for consideration of potential transfer to either Lake Dunlap or Gonzales. In order to maximize the uncommitted firm yield of Canyon Lake which could be made available to firm-up diversions under the GBRA Calhoun Canal Division (CCD) rights at upstream locations, GBRA and other hydropower rights as well as Central Power & Light

H-1 Company (CP&L) once-through cooling rights near Victoria were subordinated to Canyon Lake. Subordination, in this case, means that inflows to Canyon Lake would not be required to be released to meet permitted hydropower tlow rates downstream of Canyon Lake or CP&L once-through cooling rights near Victoria, but instead would be available for storage in Canyon Lake. As hydropower subordination results in the conversion of a non consumptive use to storage or consumptive use, water rights junior to Canyon Lake located on the mainstem of the Guadalupe downstream of Lake Dunlap (including the recent application by the City of Victoria) were assumed to be senior to Canyon Lake. All other water rights with the exception of those upstream of and junior to Canyon Lake were included in these analyses. Furthermore, it was assumed that CP&L needs for makeup cooling water could be satisfied by delivery of SAWS treated effluent to a point on the San Antonio River near Goliad and diverted into Coleta Creek Reservoir (Section 3.42). This water replacement scenario would allow CP&L's existing 20,000 acft/yr run-of-the-river right and 6,000 acft/yr (average) contract with GBRA to be converted into Canyon Lake firm yield. This conversion could result in an increase in uncommitted Canyon Lake firm yield of 8,157 acft/yr at Lake Dunlap or 7,232 acft/yr at Gonzales. As the conversion could be accomplished by amendment or abandonment of the CP&L run-of-the-river right and termination or transfer of the GBRA contract, it was assumed that Trans-Texas or other instream tlow criteria (except those related to the hydropower operations at Canyon Dam) were not applicable. SAWS treated eftluent was excluded from all firm availability analyses in order to avoid overestimation of water available for diversion under existing rights located below the confluence of the Guadalupe and San Antonio Rivers and to acknowledge the possibility that SAWS effluent could be considered to be property of SAWS and be traded or used for mitigation purposes. The Edwards Aquifer pumpage scenario proposed by SAWS results in an average annual pumpage of 368,000 acft/yr which represents a reduction of 32,000 acft/yr from the 400,000 acft/yr pumpage scenario outlined in Senate Bill 1477. The 368,000 acft/yr pumpage scenario incorporates water conservation, lease of irrigation rights in Medina and Uvalde Counties, four proposed recharge enhancement projects in the Nueces River Basin,

H-2 and summer "peak shaving" through surface water importation from the Guadalupe River. The Texas Water Development Board (TWDB) has applied their Edwards Aquifer model to simulate the combined effects of the various aspects of the SAWS pump age scenario and produced revised sets of springflows for Comal, San Marcos, and other smaller springs. Changes between the simulated springflows under the 368,000 acft/yr pumpage scenario (Appendix F) and those which occurred historically have been incorporated in the Guadalupe -San Antonio River Basin Model (GSA Model) and used in the estimation of Canyon Lake firm yield and firm water availability at Lake Dunlap and Gonzales. As presented in Appendix G, the firm yield of Canyon Lake is about 600 acft/yr to 2,000 acft/yr greater under the 368,000 acft/yr pumpage scenario than under the 400,000 acft/yr pumpage scenario depending upon the degree of hydropower subordination.

Methodology Firm availability for diversions at Lake Dunlap or Gonzales is defined to be the maximum diversion which can be obtained in every year during the 1934-89 period in accordance with a fixed monthly demand pattern utilizing a combination of water available under existing rights transferred from downstream, unappropriated flow, and Canyon Lake firm yield. The methodology employed to quantify each component of water available and to combine these components into a composite firm yield is described in the following paragraphs. The GSA Model was used to compute the uncommitted firm yield of Canyon Lake if diverted at Lake Dunlap or Gonzales subject to the assumptions outlined in the previous subsection and to simulate resulting streamflows throughout the Guadalupe - San Antonio River Basin. Monthly flows passing Canyon Dam and flowing over the Saltwater Barrier were extracted from the output summaries for use in determining water available for upstream diversion under either 40,000 acft/yr or 80,000 acft/yr of GBRA CCD water rights. Since the flows passing Canyon Dam in this simulation are representative of storage releases and inflow passage necessary to satisfy contractual obligations and GBRA CCD rights presently diverted at the Saltwater Barrier, respectively, it was assumed that these flows would not change if diversions under the senior rights were to be made at Lake

H-3 Dunlap or Gonzales instead. In addition, the flows passing the Saltwater Barrier in this simulation were assumed equivalent to the unappropriated t1ow at the Saltwater Barrier. After modifications to facilitate simulation of unique 56-year sequences of monthly t1ows passing Canyon Dam and/or exports from selected control points, the GSA Model was used to compute monthly water availability at Lake Dunlap and Gonzales under both 40,000 acft/yr and 80,000 acft/yr of GBRA CCD rights by simulating the export of all unappropriated t1ow at the Saltwater Barrier and excluding the selected portion of the GBRA CCD rights. Water availability under the GBRA CCD rights was computed both with and without Trans-Texas Environmental Criteria for Instream Flows although application of such criteria to diversions made under existing water rights is an issue which has not yet been clarified within the Trans-Texas Water Program. Consideration of Trans Texas Environmental Criteria for Freshwater Inflows to Bays and Estuaries was not necessary as flows over the Saltwater Barrier remain essentially unchanged. The GSA Model was used to compute monthly unappropriated flows available at Lake Dunlap and Gonzales by including unappropriated flows at the Saltwater Barrier and exporting water available under the selected portion of the GBRA CCD rights from either Lake Dunlap or the Guadalupe River near Gonzales. Availability of unappropriated flows was computed both with and without Trans-Texas Environmental Criteria for Instream Flows and for Freshwater Inflows to Bays and Estuaries. Water diverted under existing GBRA CCD rights and from unappropriated flows was then combined to obtain gross water availability. Although gross water availability is highly variable from month to month, actual quantities of water diverted from the Guadalupe River for SAWS and/ or others will most likely adhere to a seasonal variation pattern with the greatest demands occurring during the summer months. This is particularly true with respect to potential diversions by SAWS as it is their intent to make their Edwards Aquifer pumpage more uniform by maximizing importation of surface water in the summer months. Figure H-1 illustrates an approximation of SAWS intended utilization of supplemental surface water to level off Edwards Aquifer pumpage. SAWS supplemental surface water demand patterns as shown in Figure H-1 were used in the estimation of firm availability.

H-4 35,000 - -

30,000 ...... • •• :c •• • • zf- •• • • ·~ I 0 25,000 •••• .. • • .. •• ::::iE •• ... ·-·- - • "· •• I • .~ •• f •• •• ...... ~ • () •• •• ' •• I 20,000 ••• -~ '· •• ~ ' ~. , ·. . • • •• 0 •• • ,.--·' z •• • • -.,, ., . ..-·j <( 15,000 •• .. · .~ ~'· ""--· ::::iE _.... ~ .. w ~-~ ~-- ~--- 0 ~·--. a: w 10,000 - ;:~ 5,000

0 ' JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH

TRANS TEXAS WATER PROGRAM I - SAWS EDWARDS AQUIFER PUMPAGE (167,320 ACFT/YA) WEST CENTRAL STUDY AREA --• SAWS WATER DEMAND WITH 10,000 ACFT/YR SUPPLEMENTAL SURFACE WATER - • - SAWS WATER DEMAND WITH 73,000 ACFT/YR SUPPLEMENTAL SURFACE WATER • • • • • SAWS WATER DEMAND WITH 113,000 ACFT/YR SUPPLEMENTAL SURFACE WATER SAWS SUPPLEMENTAL SURFACE lil~ WATER DEMAND PATTERNS HDR Engineering, Inc. FIGURE H-1 Because water available at Lake Dunlap or Gonzales under the GBRA CCD rights and/or unappropriated flow is so highly variable, portions of the uncommitted yield of Canyon Lake were made available to meet monthly demands as necessary to obtain an estimate of firm availability. Firm availability was calculated using a spreadsheet analysis considering run-of-the-river water and "banked storage" in Canyon Lake during the July, 1947 through February, 1957 critical drought period. The procedure incorporated in the spreadsheet is illustrated in Figure H-2 and summarized as follows: 1) Select portion of firm yield of Canyon Lake made available to firm-up run-of the-river water at specified diversion point (Lake Dunlap or Gonzales).

2) Select trial estimate of combined annual firm availability.

3) Compute monthly portion of estimated annual firm availability based on corresponding SAWS supplemental surface water demand pattern.

4) Satisfy monthly portion of estimated annual firm availability to the extent possible from available run-of-the-river water first, and then utilize releases from a Canyon Lake banked storage account for the remainder. Increase or decrease the banked storage account balance in Canyon Lake as appropriate in each month.

5) Repeat steps 3 and 4 for each month during the critical drought. If the banked storage account balance is negative (or overdrawn) at the end of the critical drought, return to step 2 and select a reduced trial estimate. If the banked storage account balance is positive at the end of the critical drought, return to step 2 and select an increased trial estimate. When the banked storage account balance at the end of the critical drought is approximately zero, annual firm availability has been determined.

As is apparent in Figure H-2, run-of-the-river water is a significant component of the firm availability during the first seven years of the critical drought permitting the accrual of a sizeable banked storage account balance. During the final three years of the critical drought, however, banked storage becomes the dominant component of firm availability. While any channel losses affecting delivery of stored water to Lake Dunlap or Gonzales are adequately accounted for, increased evaporation losses due to banked storage are not adequately accounted for in this methodology. Preliminary analyses indicate that a more accurate accounting for evaporation losses could reduce the estimates of firm availability

H-6 0

CRITICAL DROUGHT PERIOD (JULY,1947 --<>FEBRUARY, 1957) ~ROTR .STORAGE

70000

60000 f 50000 ~ w 0 z 40000 :5 ~ w 30000 ~ 0 !i; 20000 c w l<: z 10000 ~

-10000

CRITICAL DROUGHT PERIOD (JULY, 1947 ->FEBRUARY, 1957)

TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA

EXAMPLE ILLUSTRATION OF FIRM AVAILABILITY CALCULATION

HDR Engineering, Inc. FIGURE H-2 presented herein by about 4 percent. It is recommended that modifications necessary to allow computation of firm availability within the GSA Model (thereby more accurately accounting for evaporation losses on banked storage) be undertaken in a subsequent phase of the Trans-Texas Water Program. Results Firm availability was estimated at Lake Dunlap and near Gonzales based on diversions under 40,000 acft/yr and 80,000 acft/yr of GBRA Calhoun Canal Division rights made firm to the extent possible by a range of allocations from the uncommitted firm yield of Canyon Lake both subject to and independent of Trans-Texas Environmental Criteria. Firm availability was also computed considering the potential diversion of unappropriated flows in addition to water available under existing rights. Comprehensive summaries of estimated firm availability at Lake Dunlap and near Gonzales are included in Tables H-1 and H-2 as well as in Figures H-3 through H-6. All estimates of firm availability assume that the portion of Canyon Lake firm yield resulting from the conversion of the CP&L run of-the-river rights and GBRA contract for Coleto Creek Reservoir makeup water to Canyon Lake firm yield would be allocated to firm-up available run-of-the-river water. Following are a few key observations made upon review of the firm availability estimates presented herein: 1) When Trans-Texas Environmental Criteria are applied, firm availability is limited to little more than the Canyon Lake firm yield.

2) When Trans-Texas Environmental Criteria are not applied, firm availability is greater at Lake Dunlap than near Gonzales under the 40,000 acft/yr transfer of GBRA CCD rights primarily because delivery losses between Lake Dunlap and Gonzales are avoided.

3) When Trans-Texas Environmental Criteria are not applied, firm availability is greater near Gonzales than at Lake Dunlap under the 80,000 acft/yr transfer of GBRA CCD rights considering unappropriated flow because of the larger contributing watershed area and additional springflow above Gonzales.

4) SAWS supplemental surface water demand patterns which are heavily concentrated in the summer months tend to limit utilization of run-of-the-river water available under existing rights or from unappropriated flow during the other months of the year. .

H-8 Table H-1 Firm Availability at Lake Dunlap 1

Combined Firm Availability at Portion of Firm Availability at Lake Dunlap Lake Dunlap with Water Rights Canyon Lake with Water Rights Transfers (acft/yr) Transfers and Unappropriated Water Yield Made (acft/yr) Trans-Texas Available by Environmental GBRA to Firm- CP&L and CP&L and CP&L and CP&L and Criteria Up Other Water 40,000 Acft/Yr 80,000 Acft/Yr 40,000 Acft/Yr 80,000 Acft/Yr Applied (acft/yr) GBRA CCD GBRA CCD GBRA CCD GBRA CCD CP&L 2 Rights Rights Rights Rights 0 8,157 8,157 8,157 8,157 8,157

10,000 18,157 18,405 18,405 18,405 18,405 Yes 20,000 28,157 28,780 28,780 28,780 28,780

40,599 Max 48,756 49,785 49,952 49,952 49,952 0 8,157 14,703 17,914 14,703 17,914

10,000 18,157 33,657 41,591 35,694 41,591 No 20,000 28,157 49,680 62,549 58,479 62,662 I

40,599 Max 48,756 78,600 96,715 94,495 99.648 1

1 Based on 116 month critical drought period beginning July, 1947 and ending February, 1957. 2 Includes conversion of 6,000 acftlyr GBRA contract and 20,000 acft/yr run-of-the-river rights to Canyon Lake finn yield. Table H-2 Firm Availability at Gonzales 1

Combined Firm Availability at Portion of Firm Availability at Gonzales Gonzales with Water Rights Canyon Lake with Water Rights Transfers (acft/yr) Transfers and Unappropriated \Vater Yield Made (acft/yr) Trans-Texas Available by Environmental GBRA to Firm- CP&L and CP&L and CP&L and CP&L and Criteria Up Other Water 40,000 Acft/Yr 80,000 Acft/Yr 40,000 Acft/Yr 80,000 Acft/Yr Applied (acft/yr) GBRA CCD GBRA CCD GBRA CCD GBRA CCD CP&L 2 Rights Rights Rights Rights 0 7,232 7,700 7,700 7,700 7,700

10,000 17,232 18,817 18,876 18,817 18,876 Yes 20,000 27,232 30,112 30,358 30,112 30,358

35,588 Max 42,820 46,718 48,051 46,979 48,051 0 7,232 13,954 16,675 13,954 17,613

10,000 17,232 33,343 44,320 37,369 44,320 No 20,000 27,232 47,359 70,953 65,059 74,298

I !I 35,588 Max 42,820 71,260 99,612 1 106,243 116,035

120,000 120,000

110,000 110,000

100,000 100,000 12 90,000 90,000

u~ 80,000 80,000 ~ 70,000 70,000 ~ ::::; 60,000 80,000 iii :5 50,000 50,000

~C( 40,000 ~ ::;; ~ :..-- a:u:: 30,000 - 30,000 ~ 20,000 20,000

10,000 ~ I"" - 10,000 0 - 0 0 5,000 10,000 16.000 20,000 25,000 30,000 ss,ooo 40,000 45,000 CANYON LAKE YIELD MADE AVAILABLE BY GBRA (ACFT/YR)

•• ••• CP&L TRANSFER: INCLUDES CP&l'S AUN.()F·THE-RIVER RIGHT AND CANYON LAKE CONTRACT --· CP&L TRANSFER WITH 40,000 ACFT/YR CALHOUN CANAL RIGHT TRANSFER - CP&L TRANSFER WITH ~.000 ACFT/YR CALHOUN CANAL RIGHT TRANSFER AND UNAPPROPRIATED WATER

80,000 ACFT/YR WATER RIGHT TRANSFER

120,000 120,000

110,000 110,000

100,000 100,000

90,000 90,000

~ 80,000 80,000 ~ 70,000 70,000 ~ ::::; 60,000 60,000 iii :5 50,000 50,000 < _.. ;;c 40,000 ~ 40,000 ::;; ...... - a: 30,000 30,000 u:: ~ 20,000 - 20,000 10,000 - 10,000 0 ---- 0 0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 CANYON LAKE YIELD MADE AVAILABLE BY GBRA (ACFT/YR)

•• ••• CP&L TRANSFER: INCLUDES CP&L'S RUN-OF-THE-RIVER RIGHT AND CANYON LAKE CONTRACT --· CP&L TliANSFER WITH 80,000 ACfT/VR CAlHOUN CANAL RIGHT TRANSFER - CP&L TRANSFER WtTH 80,000 ACFT/YR CALHOUN CANAL RIGHT TRANSFER AND UNAPPROPRIATED WATER

TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA

FIRM AVAILABILITY NEAR LAKE DUNLAP WITH TRANS-TEXAS ENVIRONMENTAL CRITERIA HDR Engineering, Inc. FIGURE H-3 40,000 ACFT/YR WATER RIGHT TRANSFER

120,000 120,000 I I ; 110.000 110,000 I I 100.000 100,000 : i2 I I ...... 90,000 - 90,000 I I I E 80.000 ~ 80,000 ~--"" I ~~ ~ ! ...... ~~~ -ro.ooo I ~~ -ro.ooo ~~ ~ ~~ ...J 80,000 ...... 80.000 iii _.,.,. I i ~~ :5 50,000 / 50,000 ..... ~~ < / ~--~~ .... ·········· il: 40.000 " oOO,OOO :::;; .&~ .. -- ·········· . a: 30,000 ····· 30.000 iL .., ~· ·········· . 20,000 .... 20.000 v -~· ...... 10.000 .... ······ 10,000 1 I I . 0 5,000 10,000 15.000 20,000 25.000 30,000 36.000 40,000 "6,000

CANYON LAKE YIELD MADE AVAILABLE BY GBRA (ACFT/YR)

••••• CP&l. TRANSFER: INCUJDES CP&l.'S RUif.OF.l'HE-AIIIER RIGHT AND CANYON LN

80,000 ACFT/YR WATER RIGHT TRANSFER

120.000 120.000

110,000 110.000

100,000 100.000 ~· i2 90.000 90,000

E 80,000 ~.. 80,000 ~ -ro.ooo ~ -ro.ooo ~ s 80,000 80.000 iii / :5 50.000 50,000 .... ·········· . ~<( 40.000 / 40,000 :::;; ·········· a: 30,000 / .... 30,000 iL .... ·········· . 20.QOO / . 20,000 .... ·········· 10,000 . 10,000

0 0 0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 ~.000

CANYON LAKE YIELD MADE AVAILABLE BY GBRA (ACFT/YR)

••••• CP&l. TRANSFER; INCUJDES CP&L'S RUN.QF.'fHE.

TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA

FIRM AVAILABILITY NEAR LAKE DUNLAP WITHOUT TRANS-TEXAS ENVIRONMENTAL CRITERIA HDR Engineering, Inc. FIGURE H-4 40,000 ACFr{YR WATER RIGHT TRANSFER

120,000 120,000

110,000 110.000

100,000 100,000

80.000 ao.ooo ~ 80,000 80,000 ~ 70.000 70,000 ~ :J 80,000 80,000 iii :5 50,000 50.000 ~ --::t ii( -40,000 ... ::!l ~···· a: 30,000 ..--.: 30,000 iL .... ~ ~·.. 20,000 ... 20,1100 ~· 10.000 ,...... - 10,000 0 0 0 5,000 10.000 15,000 20,000 25,000 30,1100 35,000 -40,000 45,000 CANYON LAKE YIELD MADE AVAILABLE BY GBRA (ACFT/YR)

••••• CP&L TflAHSFER: INCUJDESCP&l'S AU~THE-RIVER RIGHT AND CANYON LAKE CONTRACT --· CP&l lRANSFER WITH -40,000 ACFTJVR CALHOUN CANAl. RIGHT TRANSFER - CP&l TRANSFER WITH -40.000 ACFTJVR CALHOUN CANAl. RIOHTTRANSFER AND UNAPPROPRIATED WAlCR

BO,OOO ACFT/YR WATER RIGHT TRANSFER

120,000 120,000

110,000 110,000

100,000 100,000

0: 80,000 80,000

~ 80,000 80,000

~ 70,000 70,000 ~ ::::; 80,000 80,000 iii :5 50,000 50,000 ~ ~. ii( -40,000 ... -40,000 ::!l ~ :::::-...... a: 30,000 .... 30,000 iL ~ .. 20,000 ...~ 20,000 ~ 10,000 10,000 ~ 0 - 0 0 5,000 10,000 15,000 20,000 25,000 30,000 35.000 -40,000 45,000 CANYON LAKE YIELD MADE AVAILABLE BY GBRA (ACFT/YR)

••••• CP&L TRANSFER: INCWDES CP&l'S RUN-OF·THE-fUVER RIGHT AND CANYON LAKE CONTRACT --• CP&L TRANSFER WITH 80,000 ACFT/YR CAI.JiOUN CANAL RIGHT TRANSFER - CP&L TRANSFER WITH 80,000 ACFT/YR CALHOUN CANAL RIGHT TRANSFER AND UNAPPROPRIATED WATER

TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA

FIRM AVAILABILITY NEAR GONZALES WITH TRANS-TEXAS ENVIRONMENTAL CRITERIA HDR Engineering, Inc. FIGURE H-5 40,000 ACFTJYR WATER RIGHT TRANSFER

120,000 120,000 j

110,000 j , 110,000 ' ..... j.. 100,000 ' 100,000 r iE' 110,000 v 110.000

80,000 l ' / 10,000 ~(J ~ / /!: 70.000 v ...... :J 10.000 / .... iii j .... :5 50,QOO / .... 50,000 < " / .... .,...... ,. ... ~ 40,000 ... ~ L..~ ... -- ... ·········· a: 30,000 ... .. 30,000 u:: ~ .. ~ 20.000 ... .. ·········· 20,000 v ·········· 10,000 ... .. 10,000 0 0 0 ..... 10,000 15,000 20,000 215,000 30,000 ss,ooo 40,000 <5,000 CANYON LAKE YIEI.O MADE AVAILABLE BY GBRA (ACFT/YR) ..... CPIL TRANSFER: NCLUDES CPII.'S RlJN.OF-"fHE.fUIIEA AIClHT ANDCNI'ION LAJi 40,000 N:Fff'(R CAUKlUN CANAL Rll»tT 1lWISFEII - CPIL TRAHSfBI WIT>i 40,000 N:Fff'(R CAUKlUN CANAL AIGHT'IlWISFEII AND UNAI'PAOI'AIATED WIIlER

80,000 ACFT/YR WATER RIGHT TRANSFER

120,000 r ...... 110,000 110,000

100,000 v i _...... iE' 110,000 - / ~ / ...... ~ 10,000 .. 10,000 ~...... ~ 70,000 /: ~, 5 10,000 eo.ooo iii i ! :5 50,000 / 50,000 / < I ./ I ... ~ 40,000 ... ~ ,!...... a: 30,000 / .. ' 30,000 j ... u:: .. ·········· 20,000 / ... 20,000 .. I 10,000 .... ··········· 10,000 I 0 I 0 0 5,000 10.000 15,000 20,000 25,000 30,000 SS,OOO 40,000 <5,000 CANYON LAKE YIELD MADE AVAILABLE BY GBRA (ACFT/YR)

••••• CP&L T'RNISFER: INCLUO£S CPI.L'S RUNi 10,000 N;Frf'(R CAU10UN CANAL RIGKTTRAHSFBI - CPII. mAHSFEA WIT>i eo,ooo >CFff'(R CAUIOUH CANAL AlliKT TlWISFEII AND UNAI'PAOPNAlED WIIlER

TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA

FIRM AVAILABILITY NEAR GONZALES WITHOUT TRANS-TEXAS ENVIRONMENTAL CRITERIA HDR Engineering, Inc. FIGURE H-6 APPENDIX I

ERRATA To: Recipients of Phase I Interim Report

From: David Wheelock

Date: November 13, 1994 Memorandum

Subject: Errata Sheets Phase I Interim Report West Central Study Area Trans-Texas Water Program

The attached sheets from the Phase I Interim Report are being reissued with revisions to correct minor errors inadvertently conJ4ined in the original printing of the report. The following is a listing of the sheet numbers, contents, and revisions made.

Page Number Page Contents Description of Revisions 2-14 Table 2-3 Population Year 2050 (last column of table) projections added to Projections for River Basins replace missing digits in previous printing. and Adjacent Areas

2-64 Table 2-18 Municipal Water Year 2050 (last column of table) projections added to Demand Projections for replace missing digits in previous printing. River Basins and Adjacent Areas 2-67 Table 2-19 Industrial Water Year 2050 (last column of table) projections added to Demand Projections for replace missing digits in previous printing. River Basins and Adjacent Areas 2-82 Table 2-24 Total Water Year 2050 (last column of table) projections added to Demand Projections for replace missing digits in previous printing. River Basins and Adjacent Areas 2-85 Table 2-25 1990 Total groundwater use (last column of table) data added to Groundwater Use-- 33 replace missing digits in previous printing. County West Central Area 2-86 Table 2-26 1990 Surface Total groundwater use (last column of table) data added to Water Use-- 33 County replace missing digits in previous printing. West Central Area 3-224 Figure 3.13-3 Changes in Units of vertical axis of Streamflow Decile graphs changed Streamflow, Medina Lake, from "Acft/Month" to "Acft/Year". Alternative S-13 3-261 Figure 3.15-3 Changes in Label of vertical axis of Streamflow Decile graphs changed Streamflow, Cibolo from "Monthly Median Streamflow, Acft/Month" to Reservoir, Alternative S-15 "Average Streamflow, Acft/Year". Phase I Interim Report Errata page 2 of 2

3-279 Figure 3.16-3 Changes in Units of vertical axis of Streamflow Decile graphs changed Streamflow, Goliad from "Acft/Month" to "Acft/Year". Reservoir, Alternative S-16

3-307 Figure 3.18-2 Changes in Units of vertical axis of Streamflow Decile graphs changed Streamflow, San Marcos from "Acft/Month" to "Acft/Year". River Diversion, Alternative G-13

3-320 Figure 3.19-2 Changes in Units of vertical axis of Streamflow Decile graphs changed Streamflow, Lake Dunlap from "Acft/Month" to "Acft/Year". Diversion, Alternative G-14

3-321 Figure 3.21-3 Changes in Units of vertical axis of Streamflow Decile graphs changed Streamtlow, Cuero from "Acft/Month" to "Acft/Year". Reservoir, Alternative G-16

3-372 Figure 3.22-3 Changes in Units of vertical axis of Streamflow Decile graphs changed Streamflow, Guadalupe from "Acft/Month" to "Acft/Year". River with Lindenau Reservoir, Alternative G-17

3-373 Figure 3. 22-4 Changes in Units of venical axis of Streamflow Decile graphs changed Streamflow, Sandies Creek from "Acft/Month" to "Acft/Year". at Lindenau Reservoir, Alternative G-17

3-399 Figure 3.23-3 Changes in Units of vertical axis of Streamflow Decile graphs changed Streamflow, McFaddin from "Acft/Month" to "Acft/Y ear". Reservoir, Alternative G-18 Table 2-3 Population Projections for River Basins and Adjacent Areas--West Central Study Area Trans-Texas Water Pro2ram Projection3 2 1 1990 RIVER BASIN Use 2ooo I 2010 I 2020 I 2o3o I 2o4o I 2050 NUECES Total In-Basin 165,139 194,657 220,567 241,683 262,746 283,247 303,748 Study Area Subtotal4 110,733 132,470 152,305 169,160 186,554 203,616 220,678 Remainder of Basin 54,406 62,187 68,262 72,523 76,192 79,631 83,070

SAN ANTONIO Total In-Basin 1,270,884 1,532,451 1,838,947 2,183,948 2,613,416 3,035,968 3,458,520 Adjacent Area5 450 511 562 722 665 722 779 Study Area Subtotal 1,271,334 1,532,962 1,839,509 2,184,550 2,614,081 3,036,690 3,459,299

GUADALUPE Total In-Basin 302,409 375,420 460,254 532,452 593,985 640,608 687,231 Adjacent Area' 48,250 55,424 63,504 70,154 75,650 80,430 85,210 Study Area Subtotal 350,659 430,844 523,754 602,606 669,635 721,038 772,441

LOWER COLORADO Total In-Basin 709,456 920,081 1,124,397 1,340,653 1,566,477 1,712,900 1,859,323 Adjacent Area7 73,250 83,700 91,968 98,758 106,886 114,435 121,984 Subtotal 782,706 1,003,781 1,216,365 1,439,411 1,673,363 1,827,335 1,981,317 Adjacent Inland Area" 153,584 236,120 320,385 409,553 558,156 654,821 751,476 Study Area Subtotal 936,290 1,239,901 1,537,190 1,848,964 2,231,519 2,482,156 2,732,793

RIVER BASIN TOTALS 2,447,888 3,022,609 3,644,165 4,298,736 5,036,624 5,672,723 6,308,822 STUDY AREA 2,669,016 3,336,177 4,052,758 4,805,280 5,701,789 6,443,500 7,185,211

'Study Area 2 1990 Census, U.S. Bureau of the Census, U.S. Department of Commerce 'Texas Water Development Board, High Case for 1990 through 2040, with extrapolation to 2050 at same rate as projected for 2030-2040, April 1992, Austin, Texas. 4 0nly counties of Nueces Basin included in study area (Uvalde, Medina, Zavala, Frio, Atascosa, and parts of Bexar, Wilson and Kames). 5Part of Goliad County located in adjacent San Antonio-Nueces Coastal Basin. 'Part of Victoria County located in adjacent Lavaca-Guadalupe Coastal Basin, plus all of Refugio and Calhoun counties. 7Parts of Colorado, Wharton. and Matagorda counties located in adjacent coastal basins. 8Parts of Fayette, Lee, Wi11iamson, and Burnet counties located in adjacent basins. Note: Texas population in 1990 was 16,986,510. TWDB projections of Texas population for 2000 is 20,257,960 and for 2050 is 36,308,602 (1.27% compound annual growth rate).

2-14 Table 2-18 Municipal Water Demand Projections for River Basins and Adjacent Areas West Central Area-- Trans-Texas Water Pronams Projections in Acre-Feef 1 1990Z BASIN Use 2ooo I 2010 I 2020 I 2030 l 2o4o I 2050 NUECES Total In-Basin 32,450 41,412 44,834 47,205 50,815 54,241 57,667 Study Area Subtotal• 20,722 27,356 30,012 31,995 34,995 37,886 40,m Remainder of Basin 11,728 14,056 14,822 15,210 15,820 16,355 16,890

SAN ANTONIO Total In-Basin 239,393 352,963 404,974 460,729 545,243 626,733 708,223 Adjacent Area5 59 80 83 84 90 96 102 Study Area Subtotal 239,452 353,043 405,057 460,813 545,333 626,829 708,325

GUADALUPE Total In-Basin 52,958 76,247 88,135 97,199 106,717 113,468 120,219

Adjacent Area' 8.165 9,458 ~ 10,922 1L590 12,126 ~ Study Area Subtotal' 61,123 85,705 98,477 108,121 118,307 125,594 132,881

LOWER COLORADO Total In-Basin 138,203 206,215 241,246 278,171 322,217 348,944 375,671 Adjacent Coastal Area7 10,904 14,231 14,842 15,190 16,091 16,866 17,641 Study Area Subtotal 149,107 220,446 256,088 293,361 338,308 365,810 393,312 Adjacent Inland Area1 27,724 5!,358 66,612 81,708 109,000 126,958 144,916 Study Area Subtotal 176,831 271,804 322,700 375,069 447,308 492,768 538,228

RIVER BASIN TOTALS' 463,004 676,837 779,189 883,304 1,024,992 1,143,386 1,261,780 STUDY AREA TOTALS10 498,128 737,908 856,246 975,998 1,145,943 1,283,077 1,420,211

'Study.A=l 1As reported to and/or estimated by the Texas Water D"""lopment Board. 'Texas Water D"""lopment Boanl, High Case for 1990 through 2040, with extrapolation to 2050 at same rate as projected for 2030-2040, Apri11992, Austin, Tc:zas. 'Counties of Nueces Basin included in study area arc: Uvalde, Medina, Zavala, Frio, Atascosa, and parts of Bexar, Wilson and Kames. 'Part of Goliad County located in adjacent San Antonio-Nueces Coastal Basin. "Part of Victoria County located in adjacent Lavaca-Guadalupe Coastal Basin, plus all of Refugio and Calhoun counties. 'Parts of Colorado, Wharton, and Matagorda counties located in adjacent coastal basins. "Parts of Fayette, Lee, Williamson, and Burnet counties located in adjacent basins. 'Total for counties and parts of counties located within basin boundaries. "'''otal for 33-county study area.

2-64 Table 2-19 Industrial Water Demand Projections for River Basins and Adjacent Areas West Central Area -- Trans-Texas Water Pro~rrams Projections in Acre-Feef 199.r BASIN1 Use 2ooo I 2010 I 2020 I 2o3o I 2o4o I 2050 NUECES Total In-Basin9 4,306 4,263 4,980 5,875 6,911 8,027 9,143 Study Area Subtotal' ..b!42... 1.768 2,170 2,652 3.229 3.926 4.623 Remainder of Basin 2,157 2,495 2,810 3,223 3,682 4,101 4,520

SAN ANTONIO Total In-Basin' 14,323 19,794 24,695 30,405 36,904 43,149 49,394 Adjacent Area5 0 0 0 0 0 0 __o Study Area Subtotal 14,323 -19,794 24,695 30,405 36,904 43,149 49,394

GUADALUPE Total In-Basin' 26,263 46,352 59,038 73,113 85,326 98,987 112,648

6 ; Adjacent Area 24.539 73,297 83,156 94,154 103,934 114~09 125,084 Study Area Subtotal 50,802 119,649 142,194 167,267 189,260 213,496 237,732

LOWER COLORADO Total In-Basin9 13,575 25,526 33,454 41,841 51,400 62,715 74,030

7 Adjacent Coastal Area ~082 5,022 1!,666 ~137 27,651 38,052 48,453 Subtotal 15,657 30,548 45,120 63,978 79,051 100,767 122,483

Adjacent Inland Area• 376 638 836 1,044 1,297 1~09 !,721 Study Area Subtotal 16,033 31,186 45,956 65,022 80,348 102,276 124,204

RIVER BASIN TOTALS9 58,467 95,935 122,167 151,234 180,541 212,878 245,215 STUDY AREA TOTALS10 83,307 172,397 215,015 265,346 309,741 362,847 415,953

'Study Area 1As reported to and/or estimated by the Texas Water Development Board. "''cxas Water Development Board, High Case for 1990 through 2040, with extrapolation to 20SO at same rate as projected for 2030-2040, Apri11992, Austin, Texas. 'Counties of Nueces Basin included in study area are: Uvalde, Medina, Zavala, Frio, Atascosa, and parts of Bexar, Wilson and Kames. 'Part of Goliad County located in adjacent San Antonio-Nueces Coastal Basin. "Part of VICtoria County located in adjacent Lavaca-Guadalupe Coastal Basin, plus all of Refugio and Calhoun counties. 'Parts of Colorado, Wharton, and Matagorda counties located in adjacent coastal basins. 'Parts of Fayette, Lee, Williamson, and Burnet counties located in adjacent basins. "''otal for counties and parts of counties located within basin boundaries. "'I'otal for 33-<:ounty study area.

2-67 Table 2-24 Total Water Demand Projections for River Basins and Adjacent Areas West Central Area - Trans-Texas Water Pro2r3.m Projections in Acre-Feef 199~ BASIN' Use 2ooo I 2010 I 2020 I 2o3o l 2o4o I 2050 NUECES Total In-Basing 612,217 557,543 517,960 513,897 519,186 524,462 529,747 Study Area Subtotal• 555.503 501.826 461.468 457.295 461.551 465.860 470.173 Remainder of Basin 56,714 55,717 56,492 56,602 57,635 58,602 59,574

SAN ANTONIO Total In-Basing 357,901 469,604 526,084 592,302 693,100 780,706 868,325 5 Adjacent Area 403 586 587 ~ 592 597 ~ Study Area Subtotal 358,304 '470,190 526,671 592,888 693,692 781,303 868,928

GUADALUPE Total In-Basing 116,519 196,476 220,105 247,655 268,945 288,998 309,066 Adjacent Area6 81.440 124.965 134.594 145.127 153.409 164.352 175.300 Study Area Subtotal 197,959 321,441 354,699 392,782 422,354 453,350 484,366

LOWER COLORADO Total In-Basin9 374,659 392,382 440,891 488,667 545,687 587,499 629,321 Adjacent Coastal Area7 655,943 518384 509.061 497.277 484.558 478.784 469.006 Subtotal 1,030,602 910,766 949,952 985,944 1,030,245 1,066,283 1,098,327 Adjacent Inland Area1 34,637 73.854 88.387 103.918 131.385 149.414 167.958 Study Area Subtotal 1,065,239 984,620 1,038,339 1,089,863 1,161,630 1,215,697 1,266,242

RIVER BASIN TOTALS9 1,461,296 1,616,005 1,705,040 1,842,521 2,026,918 2,181,665 2,336,459 STUDY AREA TOTALS 10 2,177,005 2,278,077 2,381,177 2,532,828 2,739,262 2,916,210 3,089,709

'Study Area 'As reported to and/or estimated by the Texas Water Development Board. 'Texas Water Development Baud, High Case for 1990 through 2040, .,.;th extrapolation to 2050 at same rate as projccted for 2030-2040, April1992, Austin, Texas. 'Counties of Nucccs Basin included in study area arc: Uvalde, Medina, Zavala, Frio, Atascosa, and parts of Bexar, Wilson and Kames. 'Part of Goliad County located in adjacent San Antonio-Nueces Coastal Basin. 'Part of Victoria County located in adjacent Lavaca-Guadalupe Coastal Basin, plus all of Refugio and Calhoun counties. 'Parts of Colorado, Wharton, and Matagorda counties located in adjacent coastal basins. 'Parts of Fayette, Lee, Williamson, and Burnet counties located in adjacent basins. 'Total for counties and parts of counties located within basin boundaries. '"Total for 33-county study area.

2-82 Table 2-25 1990 Groundwater Use -- 33-County West Central Area Trans-Texas Water Progam 1990 Use2 (Acre-Feet) Steam- COUNTIES1 Municipal Industrial Electric Irrigation Mining livestock Total Atascosa 5,670 0 3,622 47,208 664 160 57,324 Bandera 1,417 0 0 151 20 260 1,848 Bastrop 6,234 26 0 323 10 572 7,165 Bexar 224,762 13,911 1,408 27,399 1,319 137 268,936 Blanco 646 0 0 425 0 443 1,514 Burnet 1,240 8 0 114 174 410 1,946 Caldwell 3,589 0 0 674 27 81 4,371 Calhoun 515 1,812 62 1,984 1 175 4,549 Colorado 2,927 96 0 44,280 993 837 49,133 Co mal 10,338 1,237 0 469 946 253 13,243 DeWitt 3,494 91 0 274 129 182 4,170 Fayette 3,397 32 0 80 7 203 3,719 Frio 3,045 0 38 81,568 313 109 85,073 Goliad 916 0 136 205 0 87 1,344 Gonzales 1,487 618 0 2,124 21 410 4,660 ; Guadalupe 4,949 131 0 1,376 8 102 6,566 Hays 11,635 293 0 0 0 66 11,994 Karnes 2,187 270 0 1,831 187 135 4,610 Kendall 1,734 2 0 274 0 312 2,322 Kerr 2,607 2 0 187 73 307 3,176 Lee 2,991 5 0 164 0 559 3,719 Uano 151 0 0 1,043 65 863 2,122 Matagorda 5,225 3,514 1,158 26,717 250 673 37,537 Medina 5,254 286 0 77,694 120 155 83,509 Refugio 1,227 0 0 0 77 56 1,360 San Saba 363 0 0 573 86 897 1,919 Travis 8,139 412 21 448 0 471 9,491 Uvalde 5,213 557 0 137,856 399 497 144,522 Victoria 11,545 489 865 13,151 2,409 763 29,222 Wharton 6,218 396 0 155,474 4 728 162,820 Williamson 14,787 233 0 18 1,654 150 16,842 W!lson 3,745 50 0 11,642 281 180 15,898 __o Zavala ~ ...,UQQ 76,296 ...... lli __n 80,138

Total 359,996 25,m 7,310 712,022 10,353 11,304 1,126,762 1Study Area. 2As reported to and/or estimated by the Texas Water Development Board. Note: Source in unpublished planning data, Texas Water Development Board, 1992.

2-85 Table 2-26 1990 Surface Water Use -· 33-County West Central Area Trans-Texas Water Pro~rram 1990 Use2 (Acre-Feet)

1 Steam-_! COUNTIES Municipal Industrial Electric Irri~tion Minine Livestock Total Atascosa 0 0 0 0 0 1,453 1,453 Bandera 28 0 0 139 0 65 232 Bastrop 0 1 2,967 322 6 859 4,155 Bexar 295 138 22,855 9,613 272 1,239 34,4U Blanco 258 0 0 58 0 110 426 Burnet 2,286 1,108 0 186 762 410 4,752 Caldwell 1,342 0 0 701 0 735 2,778 Calhoun 3,401 22,727 0 33,437 0 116 59,681 Colorado 0 982 0 172,200 30,974 558 204,714 Comal 77 2,011 0 10 0 63 2,161 DeWitt 62 0 0 11 0 1,658 1,731 Fayette 0 0 11,701 320 0 1,834 13,855 Frio 0 0 0 1,665 0 988 2,653 Goliad 0 0 12,029 480 0 797 13,306 Gonzales 2,345 247 0 1,416 0 3,698 7,706

Guadalupe ; 4,678 1,530 0 1,270 0 929 8,407 Hays 74 0 0 320 0 610 1,004 Kames 0 0 0 203 0 1,236 1,439 Kendall 396 0 0 106 0 77 579 Kerr 3,214 26 0 663 0 75 3,978 Lee 0 0 0 119 0 839 958 Llano 2,337 0 937 79 0 45 3,398 Matagorda 0 3,293 34,757 178,110 0 447 216,607 Medina 0 0 0 79,686 0 1,405 81,091 Refugio 0 0 0 0 0 507 507 San Saba 909 0 0 5,161 0 224 6,294 Travis 106,670 5,831 6,177 352 2,288 471 U1,789 Uvalde 65 0 0 2,813 0 497 3,375 Victoria 0 19,543 22 548 0 508 20,621 Wharton 0 0 0 172,746 2,646 485 175,877 Williamson 9,695 93 0 142 59 1,358 11,347 Wilson 0 0 0 2,055 0 1,633 3,688 Zavala __o __o __o 34.626 __o 643 35.269

Total 138,132 57,530 91,445 699,557 37,007 26,572 1,050,243 'Study Area 2As reported to and/or estimated by the Texas Water Development Board. Note: Source in unpublished planning data, Texas Water Development Board, 1992.

2-86 MEDINA RIVER NEAR RIOMEDINA ~.--.--,--T~~~~~~~~~~~--,-, - ;:g - :::;;--... Dtototo~~~wtt ~~ ~~ (l)t: ..... wo ~~·- w .. > .. c( - , __ 1•. l•n .n l•n.,_ lin,_ n n ,_ ~·~·-·~,~·~·~·~·~·~·~·~ .... ·- fl- fl- n- ...... MONTHS STREAMFLOW DECILES

,..... GUADALUPE RIVER AT SALTWATER BARRIER GUADALUPE RIVER AT SALTWATER BARRIER ;: - 0 ...... it 1110.01111 :::;; c( ;: w- g - a.: :J: - ...... ,z...... :::;;- ~ ~ '"'" a>-w ... ~~~-- .... :::;;0 Cl) &&. ,...,.. >-~ -411.000 wo _, Clc( :J: .... i:i-w ·- ~ lll,lm :::;; ;;: - •n 11n , __ OfA ,_ ll,_ ,_ .,_ at_ .. _...... ··- n- -·-·-·-·-·-·-·-·-·-MONTHS STREAMFLOW DECILES

TRANS TEXAS WATER PROGRAM I LEGEND WEST CENTRAL STUDY AREA

• WITH PROJECT CHANGES IN STREAMFLOW 0 WITHOUT PROJECT MEDINA LAKE lil~ ALTERNATIVE S-13 HDR Engineering, Inc. FIGURE 3.13-3 ... CIBOLO CREEK AT FALLS CITY ...... CIBOLO CREEK AT FALLS CITY § -·-- -- 31: ..... -- "" :::E~ g - 1&...... ~x - 1-- .,z It·~... ~g iijt 1------wo ••- -- :::E~ >- ~~, -' w :I:... ~ r- -- -- z ...... 0 :::E .n i • II j •• 1l.n .,~, ...n_.., .....,.,.,._.., ...,. ....I""', n..,.,., l ] I I I • II -.~- -·~·~~~~-'~·-~~·-~~·~ - MONTHS STREAMFLOW DECILES

GUADALUPE RIVER AT SALTWATER BARRIER GUADALUPE RIVER AT SALTWATER BARRIER ·~~----.--.--,--,--r-,--.--.--.--,--, ·- -- -- ~ ·-i=ot--+ I IIIII I I I I I I I 1&. ·------·- :::E ...I~ 1&. - ~x-- - .,z...... :::;: i' ·- 0 ~:::E .... m~ ...... a-;:: ... Ill!;: wo ~o,.- :::Ece....,. >-- ~~ -' w 1,0110,1110 :I: ~ ..... onlln ~ -~~l~l~l~l~l~l~l~l~l~l~l~l • 'ICI'A I tt.... IJt~lIJ Jt- I 11,ft .... I h.-..1 ...... I n ..... T ...... '11·11ft MONTHS STREAMFLOW DECILES

TRANS TEXAS WATER PROGRAM I LEGEND WEST CENTRAL STUDY AREA

• WITH PROJECT CHANGES IN STREAMFLOW 0 WITHOUT PROJECT CIBOLO RESERVOIR I-il~ ALTERNATIVE -15 HDR Engineering, Inc. FIGURE 3.15-3 SAN ANTONIO RIVER AT GOLIAD SAN ANTONIO RIVER AT GOLIAD ..... t,10D,0110 3: 0 .... 1-- ·-...... lL 3: ::e g ..... ~% .... r- r- ...... ~-- - ~~- r- :I: w t-- z ... ~ 0 - ::e l.lr ~ lift,_ ~ G.- a..- .,.'liN 11.- .r-11111'1. JUL - m- ~ n.- ...... ~- ""' ""' - - '"" ·- MONTHS STREAMFLOW DECILES ,., ... GUADALUPE RIVER AT SALTWATER BARRIER - GUADALUPE RIVER AT SALTWATER BARRIER 3: g 1~ 3: - ... 0 ::e ~ ...... U5- ::e- ...... oc:I: ji5!i- zg w ... ~ 1.000.000 z~; .... ::e0 ·.n _.,_,_ ~D ~ - r.n ~ .... 11-- M- M- a- M.------·~ .. ~· - ·- ~-•rr MONTHS STREAMFLOW DECILES

TRANS TEXAS WATER PROGRAM I LEGEND WEST CENTRAL STUDY AREA

• WITH PROJECT CHANGES IN STREAMFLOW 0 WITHOUT PROJECT GOLIAD RESERVOIR lil~ ALTERNATIVE S-16 HDR Engineering, Inc. FIGURE 3.16-3 ..... SAN MARCOS RIVER BELOW BLANCO RIVER SAN MARCOS RIVER BELOW BLANCO RIVER -- - .... -- I--- 1-- 3:: 3:: - g II,CIDD 0 ...1- u. IL :E "'"' ==- -- o->mx,~- ri)Z m~-- f-- f-:: Ill t: ...... wu OIL:~~·- .... wu ~~·- :Ect>-- - w ..... > 100,01111 ':I: - z>- "' ..... I :E0 - r1r I ,_ .,_ ,_ IMV ...... OCT ...... lt.... tHCIN "" - ...-- - ·- STREAMFLOW DECILES- - MONTHS - -- ...... GUADALUPE RIVER AT SALTWATER BARRIER - GUADALUPE RIVER AT SALTWATER BARRIER - ~ -- 3:: - .....u. 0 · ...... - :Iii ~ mx- ==-i:i~ ...... ~!Z 1!:~ ~g Cl) ~ I.OOQ.OIIO ··- ..... wu. at:wu. Clu :EU ~~ 1.1m,aao >!!. 40.000 ..... w ~ 11'00.000 --- ~ ~ .,_ :E - •n 1n ll~ ,_ ,_ ,_ tt~ ,.,.. - - - ...... - OCT ... OEC ...... - STREAMFLOW·- DECILES MONTHS TRANS TEXAS WATER PROGRAM I LEGEND WEST CENTRAL STUDY AREA

• WITH PROJECT CHANGES IN STREAMFLOW 0 WITHOUT PROJECT SAN MARCOS RIVER DIVERSION lil~ ALTERNATIVE G-13 HDR Engineering, Inc. FIGURE 3.18-2 ..... GUADALUPE RIVER AT LAKE DUNLAP ._ .. GUADALUPE RIVER AT LAKE DUNLAP ~ .... -' - ... ;: :: 0 - - ...... - ~~-C/)Z :i§! .... i~: jiit: C/) ~ ..... ::~ ..... wu >- (!) c( - :C-' 10MO ~- 1-z >w - §! .... c( l1n -It .. __ ..__ ~ ~ - 1 _, ·- f.lll'li'1t~ ~·lt·'"- 71~,., ~- .. ------·~ .. -· - - ... MONTHS STREAMFLOW- DECILES

...... GUADALUPE RIVER AT SALTWATER BARRIER ...... GUADALUPE RIVER AT SALTWATER BARRIER :0: ...... - 0 ...... ;: -' IL g ...... :: ... ::-ct!i ...... m~-...... 0Z :i §! ., ... (1)m~-- ... -j:: wu fil ... (!) <( 1,1110,000 ~~ ~- 40- w ...... -' X I- .... ~ z .., ... 0 :;; i•rr .. _-Ia,_ ~ ~ ltn .,_.,. .,....,., 11-1DIItl. ~· ·~ .. ,...... ,. .... ·- "" - - ··- - - .. ..- MONTHS STREAMFLOW DECILES

TRANS TEXAS WATER PROGRAM I LEGEND WEST CENTRAL STUDY AREA

• WITH PROJECT CHANGES IN STREAMFLOW 0 WITHOUT PROJECT LAKE DUNLAP DIVERSION 1-il~ ALTERNATIVE G-14 HDR Engineering, Inc. FIGURE 3.19-2 GUADALUPE RIVER AT CUERO GUADALUPE RIVER AT CUERO IOI,DOD ._... :: ..... - 0 i ..... r------::: ...... --- ::E g <( ..... ------r--- :l!x ::e-1L ...... U)Z < !1l ·- 0 ~::E .... 1-- ~~ 0wu t: .... w 0 ',IIIIQ,CIIO ::Ec Cl<( ,..-...,._, ~- :r: w ...... "------z ~ ~ ,.... - l.o liT ...... _ ...... 1.0 ...__ .. ~ --- .. .- ..__ - .. _.... - - """ - ""' --- - STREAMFLOW DECILES MONTHS __ ...... GUADALUPE RIVER AT SALTWATER BARRIER GUADALUPE RIVER AT SALTWATER BARRIER _... ~ ,.. 1L ------::E ~ ...... I 1L ~x-· ... :e- ...... '------·--- ...... CI>Z

TRANS TEXAS WATER PROGRAM I LEGEND WEST CENTRAL STUDY AREA

• WITH PROJECT CHANGES IN STREAMFLOW 0 WITHOUT PROJECT CUERO RESERVOIR lil~ ALTERNATIVE G-16 HDR Engineering, Inc. FIGURE 3.21-3 ..... GUADALUPE RIVER AT CUERO GUADALUPE RIVER AT CUERO 3: .... - 0 ~ ..... 3:: ...... :e g ~z-- !i- ...... ,- --1-- U>Z 0 i3~ ·- :i~ ..... ao ~~ wiL .._ wu 1.DOO.OOD :e~ >-- •• ~~ ..... w :I:...... z . ~ - ~ 10JIOO 1n 11n,_ .,_ ~ ~ ~ M- M- M- M------~- "- ··- M-- MONTHS STREAMFLOW DECILES

...... GUADALUPE RIVER AT SALTWATER BARRIER ...... GUADALUPE RIVER AT SALTWATER BARRIER 3: ...... 0 3:: :eIL g ....,_ IL ...... ~z-- :ii ._ .. U>Z Ww :i ~ .,... ~~ ._.. o;:: CI)IL wiL ~~ ,_ .. :;:0 >!!.. 411,000 ~- ..... :I: w ·- .....z ..... ~ 0 :e - •n 11n,_ ,..- ... ..- ...,_-. •• ....,. .. _.....,_ n.- ...- ..__ ~ ~~~ .. ~- ~ ~ - - - ·~ .. -· - ··- MONTHS STREAMFLOW DECILES

TRANS TEXAS WATER PROGRAM I LEGEND WEST CENTRAL STUDY AREA

• WITH PROJECT CHANGES IN STREAMFLOW - 0 WITHOUT PROJECT GUADALUPE RIVER WITH LINDENAU 1-il~ RESERVOIR - ALTERNATIVE G-17 HDR Engineering, Inc. FIGURE 3.22-3 KUY CREEK AT MCFADDIN KUY CREEK AT MC FAODIN "' .....

3: ...... - - -- ....~ .. 1------1-- IL ::E ~ ::;;- ..... - ...... ~% .. 0Z :i~ Wu~~ ·- i5 t: .. Clc( Wu -- '--- :Ec( ~- ,.,.. >- .... ~ i!: ,. c( ...... z 0 :E II[ .n I1D ...... o llll I ~ 1ft- ...- .... - - - ""' - ··- - - STREAMFLOW DECILES MONTHS -

...... GUADALUPE RIVER AT SALTWATER BARRIER GUADALUPE RIVER AT SALTWATER BARRIER

-_.. ~------r----- ...... ~ t-- -- IL :E ....~ -- --r---- 1n llr 1n IL -- ~% .... -- ...... ,z ~i- :i~ .... ~~ ...... II at: (/It: ·~ wu wo l,llll,liOD :Ec( Clc( >-_...... ffi- I~ i!:z ..... ~ 0 :E - •o 1n !I~ ...... ·~ - -- ...- - ...- ft.aMfo - .._,_ - "" - .. ··- -- -MONTHS STREAMFLOW DECILES

TRANS TEXAS WATER PROGRAM I LEGEND WEST CENTRAL STUDY AREA

• WITH PROJECT CHANGES IN STREAMFLOW 0 WITHOUT PROJECT MCFADDIN RESERVOIR Hl~ ALTERNATIVE G-18 HDR Engineering, Inc. FIGURE 3.23-3 SANDIES CREEK AT LINDENAU ... ~-.--r--r~--,--,--,--,--r--,-,--. 3: it0~ ,.. j----t~-+~-1-~---" rr--t-t--r-+-~_J_j w ~t::Z: :;;z !i: o ..,. I I I I rrr----t-lf-+-+J__j c;:::..::S !!il~·.. l 11111,111 >- ..J :z: ~ 1,000 0 ::;: 11n -·-·-·-·-·-·-·-·-·-·-·- MONTHS

...... SANDIES CREEK AT LINDENAU

g3: - ~- ct!!iWw ......

(1)11..!!:~ w 0 1oo.aao - ~~ w ~ 111,1111

.n .n II !I 1.n .n .,_ 51-4ID'IIO 11·70% 7'1- ., 11-2MI. 21~ ~ r .... ~-- tt-101:1% STREAMFLOW DECILES TRANS TEXAS WATER PROGRAM I LEGEND WEST CENTRAL STUDY AREA

• WITH PROJECT CHANGES IN STREAMFLOW - 0 WITHOUT PROJECT SANDIES CREEK AT LINDENAU lil~ RESERVOIR- ALTERNATIVE G-17 HDR Engineering, Inc. FIGURE 3.22 - 4 ,___ _ [§]f I C-131 -.. , [§]

-~ i '~ --·' -:-, lse-1ol "'..... ,, - I G-1•1 I G-21 I '" I G-15 I §] ~~ r-;:-:;-;1~ ~ t..:.::.:.!J

'I L-13BI ~ IG-20 II G-221 lsss-1ol ~ I G-10 I

§] IG·171 8 I G-11 I ICZ-10 I ~ --

~ [§] ~.->;l' ~ ~ ·I G-121 TRANS TEXAS WATER PROGRAM I WEST CENTRAL STUDY AREA

WATER SUPPLY ATERNATIVES lil~ .... 10 20 MUes REFERENCES IN BOXES REFER TO I I I I HDR Engineering, In·::. LIST OF ALTERNATIVES IN TABLE ES-5 sea• FIGURE ES - 11